ATMOSPHEREATMOSPHERE

atmosphereatmosphere = mixture of gases, solids, and = mixture of gases, solids, and liquids that surrounds Earthliquids that surrounds Earth

Composition of atmosphere:Composition of atmosphere:1. 0-4% water vapor: amount at any given time or place 1. 0-4% water vapor: amount at any given time or place

changes constantlychanges constantly a. percentage varies with seasons, altitude of particular a. percentage varies with seasons, altitude of particular

mass of air, and surface features beneath airmass of air, and surface features beneath air b. when volume is high percentages of other gases is b. when volume is high percentages of other gases is

slightly lowerslightly lower c. helps prevent heat loss from Earthc. helps prevent heat loss from Earth d. added by evaporation and transpiration; removed by d. added by evaporation and transpiration; removed by

condensation and precipitationcondensation and precipitation e. moist air e. moist air →→ up to 4%; dry air up to 4%; dry air →→ less than 1% less than 1% f. exists in atmosphere in all three formsf. exists in atmosphere in all three forms 1) gaseous form is source of clouds, rain, and snow1) gaseous form is source of clouds, rain, and snow 2) when changes from one state to another, heat is 2) when changes from one state to another, heat is

absorbed or released absorbed or released 3) affects atmospheric motions that create weather and 3) affects atmospheric motions that create weather and

climate climate

2. a2. atmospheric dust, ice, & salttmospheric dust, ice, & salt = three common solids found in = three common solids found in atmosphereatmosphere

a. dust:a. dust: 1) enters air by wind picking it up off ground and erodes it1) enters air by wind picking it up off ground and erodes it 2) includes mineral particles from soil, ash from fires, 2) includes mineral particles from soil, ash from fires,

volcanic dust, microscopic organisms, meteor volcanic dust, microscopic organisms, meteor particles, particles, tiny salt crystals tiny salt crystals

3) larger particles remain only briefly due to weight 3) larger particles remain only briefly due to weight causing them to fall causing them to fall

b. ice - in the form of hailstones and snowb. ice - in the form of hailstones and snow c. salt: picked up from ocean sprayc. salt: picked up from ocean spray d. role in cloud formation d. role in cloud formation

3. 3. ozone layerozone layer = acts as a shield between people and harmful = acts as a shield between people and harmful energy from sun energy from sun

a. a. ozoneozone = form of oxygen with three atoms bonded together = form of oxygen with three atoms bonded together (O(O33))

b. absorbs most of the ultraviolet (UV) radiation that enters b. absorbs most of the ultraviolet (UV) radiation that enters the atmospherethe atmosphere

c. c. ultraviolet radiationultraviolet radiation = energy from the sun that can cause = energy from the sun that can cause you to burnyou to burn

1) too much causes skin cancer1) too much causes skin cancer 2) also causes other health problems for plants and 2) also causes other health problems for plants and

animals animals d. if ozone disappeared:d. if ozone disappeared: 1) number of people dying from 1) number of people dying from

skin cancer would increaseskin cancer would increase 2) could destroy most plants2) could destroy most plants e. has become thinner all over worlde. has become thinner all over world

4. 21% oxygen4. 21% oxygen a. amount is result of natural processes that maintain a. amount is result of natural processes that maintain

chemical balance chemical balance b. used/removed by: animals, bacteria, plants, forest fires, b. used/removed by: animals, bacteria, plants, forest fires,

burning of fuels, weathering of rocksburning of fuels, weathering of rocks c. added by land and ocean plantsc. added by land and ocean plants

1) released as product of photosynthesis1) released as product of photosynthesis d. second most abundant gasd. second most abundant gas e. needed by most life formse. needed by most life forms

5. 78% nitrogen5. 78% nitrogen a. amount maintained by nitrogen cyclea. amount maintained by nitrogen cycle b. removed by nitrogen-fixing bacteria in soil on roots of b. removed by nitrogen-fixing bacteria in soil on roots of

certain plantscertain plants c. added by process of denitrificaton during decay of dead c. added by process of denitrificaton during decay of dead

organismsorganisms d. most abundant gasd. most abundant gas e. living things (plants and animals) use this to make proteine. living things (plants and animals) use this to make protein6. 1% other gases6. 1% other gases (argon, carbon dioxide, neon, helium, etc.)(argon, carbon dioxide, neon, helium, etc.)7. other components = liquids7. other components = liquids (most common = water)(most common = water)

Structure of the Atmosphere Structure of the Atmosphere (divided into layers according to (divided into layers according to major changes in major changes in

temperature)temperature)1. 1. tropospheretroposphere = closest layer to the ground = closest layer to the ground a. contains 75% of all atmospheric gases, as well as dust, a. contains 75% of all atmospheric gases, as well as dust,

ice, and liquid waterice, and liquid water b. most active portion of atmosphere because weather, b. most active portion of atmosphere because weather,

clouds, and smog occurclouds, and smog occur c. temperature decreases as altitude increasesc. temperature decreases as altitude increases 1) decreases at average rate of 6.51) decreases at average rate of 6.5ooC/kmC/km 2) stops decreasing at average altitude of 10km2) stops decreasing at average altitude of 10km d. d. tropopausetropopause = upper boundary of troposphere (varies = upper boundary of troposphere (varies

around 9 – 16 km above surface)around 9 – 16 km above surface) 1) altitude is not constant - changes 1) altitude is not constant - changes

with latitude and seasons of yearwith latitude and seasons of year 2) temperature does not change 2) temperature does not change

here = here = isothermal layerisothermal layer 3) ceiling to weather zone3) ceiling to weather zone

2. 2. stratospherestratosphere = lies above troposphere = lies above troposphere a. extends upward to altitude of 50 kma. extends upward to altitude of 50 km b. temperature increases as altitude increasesb. temperature increases as altitude increases 1) base is ~ -601) base is ~ -60ooCC 2) warmer at upper boundary = 2) warmer at upper boundary = stratopause stratopause (about 50 km (about 50 km

above surface) above surface) 3) forms another isothermal layer3) forms another isothermal layer c. contains ozone layerc. contains ozone layer d. clear and dry with strong, steady d. clear and dry with strong, steady

winds and few weather changeswinds and few weather changes e. jet streams make up lower portione. jet streams make up lower portion

3. 3. mesospheremesosphere = above stratosphere = above stratosphere a. extends to an altitude of ~ 80 kma. extends to an altitude of ~ 80 km b. temperature decreases as altitude b. temperature decreases as altitude

increasesincreases 1) upper region has coldest zone of 1) upper region has coldest zone of

atmosphere;atmosphere; drops to -90drops to -90ooCC 2) get another isothermal layer at upper 2) get another isothermal layer at upper

boundary = boundary = mesopausemesopause c. helps protect Earth from meteoroids c. helps protect Earth from meteoroids →→

may see streaks of light = may see streaks of light = “shooting” stars“shooting” stars4. 4. thermospherethermosphere = above mesosphere = above mesosphere a. temperature increases steadily with altitudea. temperature increases steadily with altitude 1) due to absorption of energy from the sun1) due to absorption of energy from the sun 2) can be more than 10002) can be more than 1000ooC in areasC in areas b. air is very thinb. air is very thin

c. has two parts:c. has two parts: 1) 1) ionosphereionosphere = lower portion = lower portion

a) altitude of 80 km to 550 kma) altitude of 80 km to 550 km b) layer of electrically charged particles (ions and free b) layer of electrically charged particles (ions and free

electrons) electrons) c) important in radio communicationsc) important in radio communications 1] AM radio waves can be bounced off layer allowing 1] AM radio waves can be bounced off layer allowing

great distances to be coveredgreat distances to be covered 2] if ions increase then can cause interference2] if ions increase then can cause interference d) area where the auroras are producedd) area where the auroras are produced

2) 2) exosphereexosphere = upper portion = upper portion a) zone of indefinite altitudea) zone of indefinite altitude

b) very few particles in airb) very few particles in air c) gases can escape to spacec) gases can escape to space d) outer layers from Van Allen Beltsd) outer layers from Van Allen Belts e) artificial satellites orbit Earth e) artificial satellites orbit Earth

in this areain this area

SOLAR ENERGY AND ATMOSPHERESOLAR ENERGY AND ATMOSPHERE1. sun is source of all energy1. sun is source of all energy2. 2. radiationradiation = transfer of energy through space by visible light, = transfer of energy through space by visible light,

ultraviolet radiation, and other forms of electromagnetic ultraviolet radiation, and other forms of electromagnetic waveswaves

a. can travel at speeds of 300,000 km/sa. can travel at speeds of 300,000 km/s b. b. wavelengthwavelength = distance from one wave crest to next = distance from one wave crest to next

1) types differ in wavelength1) types differ in wavelength c. c. electromagnetic waveselectromagnetic waves = make up all forms of radiation = make up all forms of radiation d. d. electromagnetic spectrumelectromagnetic spectrum = complete range of = complete range of

wavelengthswavelengths e. produced by all substances that have temperatures above e. produced by all substances that have temperatures above

absolute zeroabsolute zero f. almost all shorter wavelengths absorbed in upper f. almost all shorter wavelengths absorbed in upper

atmosphereatmosphere

2. 2. scatteringscattering = water droplets and dust suspended in = water droplets and dust suspended in atmosphere reflect and bend raysatmosphere reflect and bend rays

a. clouds, dust, and gas molecules affect path of radiation a. clouds, dust, and gas molecules affect path of radiation from sunfrom sun

b. sends rays out in all directions without changing b. sends rays out in all directions without changing wavelengthwavelength

c. send some back into spacec. send some back into space d. makes sky appear blue and sun appears red at sunrise d. makes sky appear blue and sun appears red at sunrise

and sunsetand sunset

3. reflection: 3. reflection: a. atmosphere is heated from Earth’s surface outward.a. atmosphere is heated from Earth’s surface outward. b. sun - source of all energy in our atmosphereb. sun - source of all energy in our atmosphere c. energy Earth receives:c. energy Earth receives: 1) 35% reflected back to space by clouds, Earth’s surface, 1) 35% reflected back to space by clouds, Earth’s surface,

and atmosphere and atmosphere 2) 15% absorbed by atmosphere2) 15% absorbed by atmosphere 3) 50% absorbed by surfaces3) 50% absorbed by surfaces * balance among these determine characteristics of * balance among these determine characteristics of

atmosphere and life that it supportsatmosphere and life that it supports d. d. albedoalbedo = fraction of solar radiation reflected by particular = fraction of solar radiation reflected by particular

surface surface 1) energy reflected back without being absorbed by 1) energy reflected back without being absorbed by

Earth’s system Earth’s system 2) earth = 0.3 (30% reflected or scattered)2) earth = 0.3 (30% reflected or scattered)

4. absorption:4. absorption: a. part is infrared rays and visible lighta. part is infrared rays and visible light b. absorbed by rocks, soil, water, and other earth materialsb. absorbed by rocks, soil, water, and other earth materials c. c. greenhouse effectgreenhouse effect = atmosphere traps infrared rays over = atmosphere traps infrared rays over

earth’s surface earth’s surface 1) absorb long wavelength infrared rays by gas molecules1) absorb long wavelength infrared rays by gas molecules 2) lower atmosphere becomes warmer making surface 2) lower atmosphere becomes warmer making surface

warmer warmer 3) objects re-emit some in changed form which prevents it 3) objects re-emit some in changed form which prevents it

from leaving atmosphere back to space from leaving atmosphere back to space 4) measurements show amount of carbon dioxide has 4) measurements show amount of carbon dioxide has

been increasing in recent years been increasing in recent years

5. variations in temperature5. variations in temperature a. earth not heated equally at all places all the timea. earth not heated equally at all places all the time b. warmth of atmosphere determined by:b. warmth of atmosphere determined by: 1) latitude1) latitude

a) average temperature higher near equator than polesa) average temperature higher near equator than poles b) direct rays heat more effectively than slanting raysb) direct rays heat more effectively than slanting rays

c. elevation c. elevation 1) high elevations cool quickly at night1) high elevations cool quickly at night 2) thinner air has less water vapor and CO2) thinner air has less water vapor and CO22 to trap heat to trap heat d. water temperature changes less than land temperatured. water temperature changes less than land temperature 1) releases heat slower than land1) releases heat slower than land 2) winds off ocean have more moderate temperature than 2) winds off ocean have more moderate temperature than

those off landthose off land e. delay in heating of atmosphere both seasonally and dailye. delay in heating of atmosphere both seasonally and daily 1) warmest time of year – July 1) warmest time of year – July 2) warmest time of day - ~2:00 in afternoon2) warmest time of day - ~2:00 in afternoon

conductionconduction = transfer of energy that occurs when molecules = transfer of energy that occurs when molecules bump into one anotherbump into one another

1. energy moves from fast moving molecules to slow moving 1. energy moves from fast moving molecules to slow moving molecules until all move at same ratemolecules until all move at same rate

2.actual contact of molecules2.actual contact of moleculesEx: warm cup in your handEx: warm cup in your hand

3. only affects very thin atmospheric layer near Earth’s surface3. only affects very thin atmospheric layer near Earth’s surface

convectionconvection = transfer of heat that occurs because of density = transfer of heat that occurs because of density differences in airdifferences in air

1. warmed air causes molecules to move apart, increasing 1. warmed air causes molecules to move apart, increasing volume and decreasing densityvolume and decreasing density

2. cold air has lower volume and higher density2. cold air has lower volume and higher density3. warm air will rise when cold air moves in and pushes it up3. warm air will rise when cold air moves in and pushes it up4. constant exchange of cold/warm produces a 4. constant exchange of cold/warm produces a convection convection

currentcurrent (wind) (wind)5. atmospheric pressure generally lower beneath a warm air 5. atmospheric pressure generally lower beneath a warm air

massmass6. main mechanism responsible for 6. main mechanism responsible for

vertical motions of air which cause vertical motions of air which cause different types of weather different types of weather

Temperature vs. HeatTemperature vs. Heat1. 1. temperaturetemperature = how rapidly or slowly molecules move around = how rapidly or slowly molecules move around a. more molecules or faster-moving molecules in given a. more molecules or faster-moving molecules in given space creates higher temperaturespace creates higher temperature b. slow moving molecules cause substance to coolb. slow moving molecules cause substance to cool c. used to measure and interpret flow of energyc. used to measure and interpret flow of energy2. 2. heat heat = transfer of energy that occurs because of a difference = transfer of energy that occurs because of a difference

in temperature between substances in temperature between substances a. direction of heat flow depends on temperaturea. direction of heat flow depends on temperature b. flows from object of higher temperature to object of lower b. flows from object of higher temperature to object of lower

temperaturetemperature c. fuels atmospheric c. fuels atmospheric processesprocesses

Heat Energy:Heat Energy:1. when added to ice molecules move more rapidly changing 1. when added to ice molecules move more rapidly changing

position creating a liquid (melting)position creating a liquid (melting)2. when liquid is heated molecules move even faster changing 2. when liquid is heated molecules move even faster changing

position creating a gas (evaporation)position creating a gas (evaporation)3. 3. sublimationsublimation = solid changes directly into a gas without = solid changes directly into a gas without

becoming a liquid becoming a liquid a. air dry, temperature below freezing a. air dry, temperature below freezing → →

ice change to water vaporice change to water vapor b. b. depositiondeposition = water vapor changes = water vapor changes

directly to solid without becoming directly to solid without becoming a liquida liquid

Ex: frost formationEx: frost formation4. water absorbs heat energy from sun4. water absorbs heat energy from sun a. causes molecules to evaporate and pass into aira. causes molecules to evaporate and pass into air b. takes place in areas near the equatorb. takes place in areas near the equator c. principal source is oceanc. principal source is ocean

Atmospheric Measurements:Atmospheric Measurements:dew pointdew point = temperature at which air is saturated and = temperature at which air is saturated and

condensation takes place condensation takes place1. often called 1. often called condensation temperaturecondensation temperature2. more water vapor the air starts with, higher its dew point2. more water vapor the air starts with, higher its dew point3. temperature of air will drop more slowly after reaching dew 3. temperature of air will drop more slowly after reaching dew

pointpoint4. also forms clouds and fog4. also forms clouds and fog5. 5. dewdew = water vapor condensed on surfaces in form of liquid = water vapor condensed on surfaces in form of liquid6. 6. frostfrost = temperature below freezing water vapor sublimes to a = temperature below freezing water vapor sublimes to a

solid solid a. not frozen dew (clear beads of a. not frozen dew (clear beads of

ice - not common)ice - not common) b. indicates temperature is low b. indicates temperature is low enough to damage growing enough to damage growing

plants plants

Vertical temperature changes:Vertical temperature changes:1. 1. adiabatic adiabatic temperature changes = result solely from temperature changes = result solely from

expansion or compression of airexpansion or compression of air a. air mass will cool off by about 10a. air mass will cool off by about 10ooC for every 1000m C for every 1000m

increase in altitude; moisture influences rateincrease in altitude; moisture influences rate b. b. dry adiabatic lapse ratedry adiabatic lapse rate = rate at which unsaturated air to = rate at which unsaturated air to

which no heat is added or removed will coolwhich no heat is added or removed will cool c. c. moist adiabatic lapse ratemoist adiabatic lapse rate = rate at which saturated air = rate at which saturated air

coolscools 1) above LCL air becomes 1) above LCL air becomes saturated and cools more saturated and cools more slowlyslowly 2) rate ranges from ~ 42) rate ranges from ~ 4ooC/1000 m C/1000 m in very warm air to almost in very warm air to almost 99ooC/1000 m in very cold airC/1000 m in very cold air

2. 2. lifted condensation levellifted condensation level (LCL) = height at which (LCL) = height at which condensation occurs condensation occurs

a. clouds form when water vapor condenses into water a. clouds form when water vapor condenses into water dropletsdroplets

b. often corresponds to base of cloudsb. often corresponds to base of clouds c. further condensation allows cloud to expand abovec. further condensation allows cloud to expand above

atmospheric pressureatmospheric pressure = ratio of weight of air to area of = ratio of weight of air to area of surface on which it presses surface on which it presses

1. force of air pushing against surface due to weight of gas 1. force of air pushing against surface due to weight of gas molecules and gravitymolecules and gravity

2. greatest at sea level and decreases as you move out 2. greatest at sea level and decreases as you move out toward spacetoward space

a. 99% of total mass of gases found within 32 km of a. 99% of total mass of gases found within 32 km of surfacesurface

b. remaining 1% extend upward hundreds of kilometersb. remaining 1% extend upward hundreds of kilometers 1) gets thinner at higher 1) gets thinner at higher

altitudesaltitudes 2) lower pressure at 2) lower pressure at

higher altitudeshigher altitudes

3. 3. standard sea level pressurestandard sea level pressure = average weight is = average weight is 14.7 lbs/in14.7 lbs/in22 (15 lbs/in (15 lbs/in22) or 10.1 N/cm) or 10.1 N/cm22

4. varies at different places due to differences in air’s density4. varies at different places due to differences in air’s density5. cold air more dense than warm air therefore higher 5. cold air more dense than warm air therefore higher

pressurepressure a. temperature is directly proportional to pressure a. temperature is directly proportional to pressure b. temperature is inversely proportional to density b. temperature is inversely proportional to density →→ air air

rises as increase in temperature rises as increase in temperature

6. acts in all directions always pushing down on us6. acts in all directions always pushing down on usEx: handEx: hand

a. measures 8” X 4” = 32 ina. measures 8” X 4” = 32 in22 X 15 lbs/in X 15 lbs/in22 = = 480 lbs. pressure480 lbs. pressure

* don’t feel because hand pushes back as much * don’t feel because hand pushes back as much as atmospheric pressure pushes downas atmospheric pressure pushes down

b. pressure pushes on body in all places but b. pressure pushes on body in all places but internal body pressure equalizes external internal body pressure equalizes external

pressurepressure

If there was no external body pressure If there was no external body pressure →→ body body would explode!!would explode!!

temperature inversiontemperature inversion = increase in temperature with height = increase in temperature with height in atmospheric layerin atmospheric layer

1. temperature-altitude relationship is inverted1. temperature-altitude relationship is inverted2. causes:2. causes: a. rapid cooling of land on cold, clear, winter night when a. rapid cooling of land on cold, clear, winter night when

wind is calmwind is calm b. warm air traps cooler air near b. warm air traps cooler air near

earth’s surfaceearth’s surface3. worsen air pollution problems by 3. worsen air pollution problems by

trapping pollution under inversion trapping pollution under inversion layerlayer

windwind = rush of air formed by imbalance between warm, less = rush of air formed by imbalance between warm, less dense air mass and cool, more dense air massdense air mass and cool, more dense air mass

1. cool air, being more dense, sinks & forces warm, less 1. cool air, being more dense, sinks & forces warm, less denser air upwarddenser air upward

2. for lower atmosphere, generally moves from areas of high 2. for lower atmosphere, generally moves from areas of high density to areas of low densitydensity to areas of low density

3. response to imbalances created by unequal heating and 3. response to imbalances created by unequal heating and cooling of Earth’s surfacecooling of Earth’s surface

4. will create areas of high and low pressure4. will create areas of high and low pressure5. usually measured in miles/hour or km/h; ships measure in 5. usually measured in miles/hour or km/h; ships measure in

knots; 1 knot = 1.85 km/hknots; 1 knot = 1.85 km/h

humidityhumidity = amount of water vapor in air = amount of water vapor in air1. depends on temperature of air1. depends on temperature of air a. cooler air a. cooler air →→ molecules close molecules close →→ less space for water less space for water

vapor vapor →→ squeezed out squeezed out b. warmer air b. warmer air →→ molecules move apart molecules move apart →→ hold more water hold more water

vaporvapor2. warm air holds more moisture than an equal volume of cold 2. warm air holds more moisture than an equal volume of cold

airair- as temperature increases the amount of moisture - as temperature increases the amount of moisture holds increases holds increases

3. 3. saturatedsaturated = air is holding all the moisture it can at a given = air is holding all the moisture it can at a given temperature temperature

RH = 100%RH = 100%

relative humidity (RH)relative humidity (RH) = amount of water vapor in air = amount of water vapor in air compared to maximum amount of water vapor air can hold compared to maximum amount of water vapor air can hold at that temperature (its capacity)at that temperature (its capacity)

1. stated as a percent1. stated as a percent2. varies with temperature2. varies with temperature3. calculated by dividing humidity by the capacity3. calculated by dividing humidity by the capacity

humidityhumidity X 100 X 100 capacitycapacity

Ex: humidity = 11Ex: humidity = 11 capacity = 22capacity = 22RH = RH = 1111 X 100 = 0.50 X 100 = 50%X 100 = 0.50 X 100 = 50%

22224. changes occur when:4. changes occur when: a. air at fixed temperature, changes as moisture enters or a. air at fixed temperature, changes as moisture enters or

leaves airleaves air b. amount of moisture in air remains same, temperature of b. amount of moisture in air remains same, temperature of

air changesair changes

specific humidityspecific humidity = actual amount of moisture in air = actual amount of moisture in air1. number of grams of water vapor in 1kg of air1. number of grams of water vapor in 1kg of air2. measured only in units of mass2. measured only in units of mass3. not affected by changes in temperature or pressure3. not affected by changes in temperature or pressure4. only a change in the amount of water vapor in air can 4. only a change in the amount of water vapor in air can

cause a changecause a change

clouds clouds = visible masses of tiny water or ice particles = visible masses of tiny water or ice particles suspended in atmosphere suspended in atmosphere

1. due to condensation of water vapor throughout large volume 1. due to condensation of water vapor throughout large volume of airof air

2. formation caused by:2. formation caused by: a. a. condensation nulceicondensation nulcei = solid matter that provides = solid matter that provides

surfaces surfaces for water condensationfor water condensation b. b. orographic liftingorographic lifting = formation of cloud when wind = formation of cloud when wind

encounters a mountain and air has no place to go but encounters a mountain and air has no place to go but upup c. collision of air masses of different temperaturesc. collision of air masses of different temperatures3. process: 3. process: a. lifted air cools a. lifted air cools →→ can’t hold can’t hold

moisture so it condenses moisture so it condenses out out →→ cloud cloud b. where air lifts will also have air b. where air lifts will also have air

descending which warms descending which warms →→ clouds re-evaporatesclouds re-evaporates

4. amount of water vapor air can hold decreases as 4. amount of water vapor air can hold decreases as temperature goes downtemperature goes down

5. 5. stabilitystability = ability of air mass to resist rising (cooling) = ability of air mass to resist rising (cooling) a. rate at which air mass cools partially depends on a. rate at which air mass cools partially depends on

temperature of surface below ittemperature of surface below it b. also affected by temperature of surrounding air masses b. also affected by temperature of surrounding air masses and temperature of air mass itselfand temperature of air mass itself c. will become unstable if cooler than surface beneath it c. will become unstable if cooler than surface beneath it 6. 6. latent heatlatent heat = energy absorbed & stored in water vapor = energy absorbed & stored in water vapor a. released when water condensesa. released when water condenses b. also involved when water b. also involved when water freezes or thawsfreezes or thaws c. can provide energy to c. can provide energy to weather systemsweather systems

7. cooling leads to condensation7. cooling leads to condensation a. a. convective coolingconvective cooling = lowering of temperature of mass of = lowering of temperature of mass of

air due to it rising and expanding air due to it rising and expanding 1) compression warms air1) compression warms air 2) expansion cools air2) expansion cools air b. forced upward movement of b. forced upward movement of

air air 1) moving air mass meets 1) moving air mass meets

sloping terrainsloping terrain 2) storms events2) storms events c. temperature changes due to one body of moist air mixing c. temperature changes due to one body of moist air mixing with another at different temperaturewith another at different temperature d. d. advective coolingadvective cooling = when wind carries warm, moist air = when wind carries warm, moist air

across cold ocean or region of landacross cold ocean or region of land

Classification of CloudsClassification of Clouds1. shape of a cloud depends on air movement that forms it1. shape of a cloud depends on air movement that forms it2. classified according to shape and altitude 2. classified according to shape and altitude 3. reach higher altitudes in equatorial areas and lower altitudes 3. reach higher altitudes in equatorial areas and lower altitudes

in polar areasin polar areas4. heights are measured above surface, not above sea level4. heights are measured above surface, not above sea level5. forms: stratus, cumulus, cirrus, and nimbus5. forms: stratus, cumulus, cirrus, and nimbus6. altitude groups: low (up to 2000 m), middle (2000 - 6000 m), 6. altitude groups: low (up to 2000 m), middle (2000 - 6000 m),

and high (above 6000 m)and high (above 6000 m)

Basic Types of Clouds:Basic Types of Clouds:1. 1. stratusstratus = low sheets or layers of clouds = low sheets or layers of clouds a. form where layer of warm, moist air lies above a layer of a. form where layer of warm, moist air lies above a layer of cool aircool air b. smooth, gray clouds that cover the whole sky and block b. smooth, gray clouds that cover the whole sky and block out the sunout the sun c. form at altitude of about 2.5 kmc. form at altitude of about 2.5 km d. usually longer than they are thickd. usually longer than they are thick e. associated with light rain and drizzlee. associated with light rain and drizzle

f. f. nimbostratusnimbostratus = thick, dark, gray layers = thick, dark, gray layers 1) associated with steady, long precipitation 1) associated with steady, long precipitation

(heavy rains/snows)(heavy rains/snows) 2) blocks out sun2) blocks out sung. g. altostratusaltostratus = form at middle altitudes = form at middle altitudes 1) thinner, can be either all liquid or mixture of liquid and 1) thinner, can be either all liquid or mixture of liquid and ice crystalsice crystals 2) dark, but sometimes produce precipitation2) dark, but sometimes produce precipitation

2. 2. cumuluscumulus = puffy, vertical growing clouds = puffy, vertical growing clouds a. form when warm, moist air rises and coolsa. form when warm, moist air rises and cools b. by vertically rising air currentsb. by vertically rising air currents c. at altitudes of 2.4 to 13.5 kmc. at altitudes of 2.4 to 13.5 km d. may extend verticallyd. may extend vertically e. height depends on speed of upward movement and e. height depends on speed of upward movement and

amount of moisture in airamount of moisture in air f. develop during the day over landf. develop during the day over land g. usually associated with fair weatherg. usually associated with fair weather

h. h. cumulonimbuscumulonimbus = thunderheads = thunderheads 1) get larger and darker on bottom1) get larger and darker on bottom 2) become dark gray with ragged edges2) become dark gray with ragged edges 3) associated with thunderstorms, heavy rain, and hail3) associated with thunderstorms, heavy rain, and hail i. i. altocumulusaltocumulus = middle altitudes = middle altitudes 1) can be either all liquid or mixture of liquid & ice crystals1) can be either all liquid or mixture of liquid & ice crystals 2) resemble white fish scales2) resemble white fish scales j. j. stratocumulusstratocumulus = low clouds which are combination of = low clouds which are combination of

stratus and cumulusstratus and cumulus

cumulonimbus stratocumulus

3. 3. cirruscirrus = feathery or fibrous clouds = feathery or fibrous clouds a. form at very high altitudes between 6 - 12 kma. form at very high altitudes between 6 - 12 km b. composed of ice crystals or supercooled waterb. composed of ice crystals or supercooled water c. can see in fair weather; sunlight passes through easilyc. can see in fair weather; sunlight passes through easily d. d. cirrocumuluscirrocumulus = composed entirely of ice crystals = composed entirely of ice crystals 1) often appear before rain or snow falls1) often appear before rain or snow falls 2) form quite rarely2) form quite rarely

e. ce. cirrostratusirrostratus = long and thin = long and thin 1) form continuous layer that sometimes covers sky1) form continuous layer that sometimes covers sky 2) vary in thickness from being almost transparent to 2) vary in thickness from being almost transparent to

dense enough to block sun or moon dense enough to block sun or moon 3) may cause halo effect around sun or moon due to ice 3) may cause halo effect around sun or moon due to ice

crystals bending light crystals bending light 4) may thicken and lower base to form altostratus 4) may thicken and lower base to form altostratus

clouds clouds

fogfog = result of condensation of water vapor in air = result of condensation of water vapor in air1. forms near surface when air close to ground is cooled1. forms near surface when air close to ground is cooled2. usually a form of stratus cloud2. usually a form of stratus cloud3. 3. radiation fogradiation fog = layer of air in contact with earth becomes = layer of air in contact with earth becomes

chilled at night below its dew pointchilled at night below its dew point a. results from lose of heat by radiationa. results from lose of heat by radiation b. also called ground fogb. also called ground fog c. usually forms on calm, clear nightsc. usually forms on calm, clear nights d. thickest in valleys and low placesd. thickest in valleys and low places

4. 4. advection fogadvection fog = form when warm moist air moves across = form when warm moist air moves across cold surface cold surface

a. common along coastsa. common along coasts b. may form over oceanb. may form over ocean5. 5. upslope fogupslope fog = formed by lifting and adiabatic cooling of air = formed by lifting and adiabatic cooling of air

as it rises along land surfaces as it rises along land surfaces6. 6. steam fogsteam fog = forms over rivers and lakes = forms over rivers and lakes a. shallow layera. shallow layer b. cool air moves over warm body of waterb. cool air moves over warm body of water

precipitationprecipitation = any moisture that falls from air to earth’s = any moisture that falls from air to earth’s surface surface

1. can have different forms depending on the temperature of 1. can have different forms depending on the temperature of the air the water passes throughthe air the water passes through

2. four main types:2. four main types: a. a. rainrain = liquid precipitation = liquid precipitation 1) large drops of water that are far apart and fall fast1) large drops of water that are far apart and fall fast 2) diameter between 0.5 mm and 5 mm2) diameter between 0.5 mm and 5 mm 3) d3) drizzlerizzle = very fine drops that are very close together = very fine drops that are very close together

and fall very slowly and fall very slowly a) diameter smaller than 0.5 mma) diameter smaller than 0.5 mm b) small amount of total precipitationb) small amount of total precipitation

4) vary from fine mist to torrential down pours4) vary from fine mist to torrential down pours

b. b. snowsnow = solid precipitation = solid precipitation 1) when water vapor changes directly to a solid1) when water vapor changes directly to a solid 2) air temperature must be below freezing2) air temperature must be below freezing 3) may fall as small pellets, individual crystals, or 3) may fall as small pellets, individual crystals, or snowflakessnowflakes 4) diameter ranges from several mm to several cm4) diameter ranges from several mm to several cm 5) small at low temperatures and larger at temp. near 05) small at low temperatures and larger at temp. near 0ooCC 6) size difference due to amount of moisture in air 6) size difference due to amount of moisture in air

c. c. sleetsleet = clear ice pellets = clear ice pellets 1) form when rain falls through layer of freezing air 1) form when rain falls through layer of freezing air 2) usually smaller than 0.3 inches in diameter2) usually smaller than 0.3 inches in diameter 3) 3) glaze iceglaze ice = thick layer of sheet ice = thick layer of sheet ice

a) rain does not freeze until strikes surface near grounda) rain does not freeze until strikes surface near ground b) weight often breaks tree limbs and power linesb) weight often breaks tree limbs and power lines c) conditions that create are called c) conditions that create are called ice stormsice storms

4) f4) freezing rainreezing rain = supercooled drops turn into ice when = supercooled drops turn into ice when come in contact with ice nucleus or something solidcome in contact with ice nucleus or something solid

5) 5) freezing drizzlefreezing drizzle = smaller supercooled drops = smaller supercooled drops

sleet

d. d. hailhail = solid precipitation in form of lumps of ice = solid precipitation in form of lumps of ice 1) drops of water freeze in layers around a small nucleus of 1) drops of water freeze in layers around a small nucleus of

iceice 2) usually formed in cumulonimbus clouds2) usually formed in cumulonimbus clouds 3) can range from 5 to 75 mm in diameter3) can range from 5 to 75 mm in diameter 4) grow larger as they are tossed up and down by rising 4) grow larger as they are tossed up and down by rising

and falling air currentsand falling air currents 5) falls when it grows too heavy for the updraft to continue 5) falls when it grows too heavy for the updraft to continue

holding it upholding it up 6) can grow larger than 6) can grow larger than

a softballa softball

Causes of Precipitation:Causes of Precipitation:1. cloud droplet must increase size 100X normal diameter1. cloud droplet must increase size 100X normal diameter2. 2. coalescencecoalescence = combination of different sized cloud droplets = combination of different sized cloud droplets

to form larger droplets to form larger droplets a. when too heavy to be supported by air, droplet fallsa. when too heavy to be supported by air, droplet falls3. 3. supercoolingsupercooling = water droplets are induced to remain liquid at = water droplets are induced to remain liquid at

temperatures below 0temperatures below 0ooCC a. droplets have temperature less than 0a. droplets have temperature less than 0ooCC b. too few freezing nuclei presentb. too few freezing nuclei present c. fc. freezing nucleireezing nuclei = condensation nuclei with crystalline = condensation nuclei with crystalline

structure like that of ice structure like that of ice 1) needed for ice crystals to form1) needed for ice crystals to form 2) increase in size until gain enough mass to fall2) increase in size until gain enough mass to fall

4. 4. cloud seedingcloud seeding = method used to attempt to cause or = method used to attempt to cause or increase precipitationincrease precipitation

a. freezing nuclei are added to supercooled cloudsa. freezing nuclei are added to supercooled clouds b. methods used:b. methods used: 1) silver iodide crystals1) silver iodide crystals 2) powdered dry ice2) powdered dry ice c. may increase precipitation from some clouds and not c. may increase precipitation from some clouds and not

othersothers d. uses:d. uses: 1) overcome droughts1) overcome droughts 2) control severe storms2) control severe storms