What is the Atmosphere?What is the Atmosphere?• The layer of gases that surrounds our

planet.

Why is it important?Why is it important?

• Our atmosphere makes life possible on our planet.

• Provides us with oxygen.• Keeps surface warm so water can

exist as a liquid.• Protects the surface from dangerous

radiation from the sun.

What is the Composition of What is the Composition of the Atmosphere?the Atmosphere?

• Nitrogen makes up 78% of our atmosphere

• Oxygen makes up 21%

• Argon makes up almost 1%

• All other gases have only trace amounts

What was Earth’s Early What was Earth’s Early Atmosphere?Atmosphere?

• The Precambrian atmosphere was composed mainly of nitrogen and carbon dioxide, along with some methane and ammonia.

• Volcanoes spewed water vapor, carbon monoxide, and even more nitrogen and carbon dioxide into the air.

• So where did the abundant oxygen that has made life as we know it come from?

What was Earth’s Early What was Earth’s Early Atmosphere cont?Atmosphere cont?

• The first life on Earth was cyanobacteria (blue-green algae).

• They used photosynthesis to turn CO2 into the food and energy they needed to survive.

• Photosynthesis gives off oxygen as a waste product.

• So over the millions of years, oxygen given off by algae built up in the atmosphere, while the amount of CO2 declined.

• Exosphere- lowest density

• Thermosphere• (Ionosphere)• Mesosphere• Stratosphere • Troposphere -highest

density

What are the Layers What are the Layers of the Atmosphere?of the Atmosphere?

Bun

Hamburger

Tomato

Lettuce

Mayonnaise

Bun

Layers

Earth

ExosphereExosphere• 500-520 kilometers above earth• This outermost layer of the atmosphere is the

closest to space and has the least amount of gas atoms and molecules

• In the exosphere, molecules and atoms escape into space.

• This layer is also where satellites orbit the Earth.

• Hottest layer due to sun’s light being converted to thermal

ThermosphereThermosphere• The thermosphere occurs from 85 to 500

kilometers from the surface of the Earth. • This atmospheric layer is called the upper

atmosphere. • The thermosphere contains thin layers of

gases, which absorb much of the sun’s light. • This causes the thermosphere to be

significantly warmer than other layers. But not as hot as exosphere

• Auroras occur and the space shuttle orbits in this layer of the atmosphere.

MesosphereMesosphere

• The mesosphere layer lies from 50-85 kilometers above the Earth.

• Meteors leave trails when hitting this layer of atmosphere, as the thick gases slow them down and they eventually burn up.

StratosphereStratosphere• The stratosphere extends from 10 to 50

kilometers above the surface of the Earth.

• Aircraft fly in this layer

• Weather balloons penetrate the stratosphere, relaying pertinent information to scientists.

• Contains the ozone layer which scatters harmful ultra-violet radiation

TroposphereTroposphere• The troposphere is the layer of the atmosphere

where the weather happens.

• Lying just above Earth, this layer extends from the surface to 10 kilometers above.

• The gases thin and temperatures drop as altitude increases.

• This layer contains half of the gases in the atmosphere and they are generally well blended.

• This layer is heated from the ground.

What is weather?What is weather?

• It is the state of the atmosphere (troposphere) at a specific time and place.

• Components of weather include air pressure, wind, temperature, humidity and precipitation

Sun’s role in weather!Sun’s role in weather!

• Solar energy from the sun strikes the Earth’s surface. This transfer in energy drives the production of all weather conditions. Examples: water cycle, wind, temperature, etc.

• What would happen if there wasn’t a sun? What type of weather would the Earth have?

Sun’s role clipSun’s role clip

What happens to the Solar Energy?What happens to the Solar Energy?

Why does the amount and intensity of Why does the amount and intensity of sunlight vary throughout the year?sunlight vary throughout the year?

– Tilt of the Earth’s axis– Position in revolution (orbit) around the sun

Which place receives the same amount and intensity of sunlight throughout the year?

– The equator

Fall(sun aims directly at equator)

Summer(northern hemisphere

tilts toward sun)

Spring(sun aims directly

at equator)

23.5º

Winter(northern

hemispheretilts away from sun)

Solarradiation

The Tilting affect!

seasons animation length of day animation

What is climate?What is climate?

1. Climate is long-term weather conditions

2. Temperature and precipitation are the most important expressions of climate

– What is Ohio’s climate?• Temperate

– Cold winters– Hot summers– Average rain/snowfall

HOW DOES CLIMATE INFLUENCE OTHER HOW DOES CLIMATE INFLUENCE OTHER ASPECTS OF THE ENVIRONMENT?ASPECTS OF THE ENVIRONMENT?

– Vegetation is the most visible expression of climate

– Animal life adapts to both climate and vegetation

– Soils develop in response to climate and vegetation

– Landforms – Water resources

Distribution of Biomes based on Distribution of Biomes based on climateclimate

What is the water cycle?What is the water cycle?• It is the movement of water to and from the

lithosphere and the atmosphere.

• 1.Energy from the sun drives the cycle causing water to evaporate.

• 2.The water vapor eventually condenses when it cools to form clouds.

• 3.Eventually the water droplets get to heavy and fall back to the earth as precipitation.

• 4.The water from the precipitation eventually runs-off into bodies of water.

The water cycle!The water cycle!water cycle animation

evaporation

Air Pressure Clips (fwd)Air Pressure Clips (fwd)

What is Air PressureWhat is Air Pressure

• air pressure is caused by the weight of the air air pressure is caused by the weight of the air pressing down on the Earth, the ocean and pressing down on the Earth, the ocean and on the air belowon the air below

• the pressure depends on the amount of air the pressure depends on the amount of air above the measuring point and falls as you above the measuring point and falls as you go higher go higher

• air pressure changes with weatherair pressure changes with weather

• air pressure is measure in pounds per square air pressure is measure in pounds per square inch. Average air pressure is 14.7 p.s.i. inch. Average air pressure is 14.7 p.s.i.

Air PressureAir Pressure• High Pressure areas: Dense Sinking air

masses which make it difficult for air to rise and form clouds.

• Results - Clear sunny weather is the result.

• Low Pressure Areas: Less dense air is able to rise resulting in cloud formation

• Results - Cloudy weather is the result.

Different Temperatures - Different Temperatures - Different Pressures Different Pressures

CoolAir

WarmAir

Denser

MorePressure

Less Dense

LessPressure

Moist surface warmed by sun

Flows toward low pressure,picks up moisture and heat

Warm,dry air

Hot, wetair

Falls, is compressed, warms Rises, expands, cools

Heat releasedradiates to space

LOWPRESSURE

HIGHPRESSURE

Cool, dryair

Condensationand

precipitation

HIGHPRESSURE

HIGHPRESSURE

LOWPRESSURE

LOWPRESSURE

View pressure systemsView pressure systems

How does differences in air pressure create wind?

Wind moves from high pressure areas to lowpressure areas because there is less molecules inthe low pressure area.

What are isobars?• Isobars connect areas of equal pressure

Close together = greater difference in air pressure

STRONG winds

Far apart = less difference in air pressures Light winds

Isobars and WindIsobars and Wind

Measuring devicesMeasuring devices

• Anemometer: measures wind speed

• Barometer: measures air pressure

Air masses clipAir masses clip

Air massesAir masses

What is an air mass?What is an air mass?

• Air mass – a section of air that has similar characteristics to the area it formed over(warm dry, warm moist, cold dry, and cold moist)

• Which air mass would be the most dense? Least dense?

Continental Arctic (cA): Continental Arctic (cA):

• Frigid – record low temperatures• Dry - very low dew points• Dense - very high barometric pressure• Usually originate north of the Arctic Circle

Siberian Express

• Usually once or twice a winter• very rarely form during the summer

because the sun warms the Arctic.

Continental polar (cP): Continental polar (cP):

• Cold and dry - stable• Usually originates in NW Territory of Canada• Influences mainly the northern USA• Responsible for clear and pleasant weather

during the summer • Usually in winter• Creates troughs in the polar jet stream• Lake effect snow in Great Lakes areas

Maritime polar (mP):Maritime polar (mP):

• Cool and moist - unstable • Originate over N. Atlantic and N.

Pacific• Main Influence - the Pacific Northwest

and the Northeast. • can form any time of the year • Generally not as cold as cPcP air masses

Maritime tropical (mT): Maritime tropical (mT):

• Warm and very moist – unstable• Originate in the Gulf of Mexico and

the Southern Atlantic Ocean• Influences the eastern USA • Most prevalent during summer • Responsible for hot, humid summer

days across the South and the East.

Continental Tropical (cT):Continental Tropical (cT):

• Very Hot and very dry – stable aloft • Originates in Desert Southwest and

northern Mexico • Occurs in the summer, rarely in winter• Usually keeps the Desert Southwest

scorching above 100oF during summer• Generally clear skies, hot, low humidity

Coriolis Effect Clip (Moving Air Coriolis Effect Clip (Moving Air masses)masses)

What is humidity?What is humidity?

• Humidity refers to the amount of moisture that is in the air (water vapor)

• It is measured with a device called a hygrometer

• What temperature of air will be more humid ? why?

• What is the temperature when the water vapor condenses?

Fronts clipFronts clip

Fronts:Fronts:

• The leading edge (front) of an air mass

• Characterized by shift/change in weather

Cold Warm Stationary

Fronts and their symbolsFronts and their symbols

What is a warm front?• It is the leading edge of a warm air mass

How does it affect the weather?• lower pressure• Warmer temperatures• Possibly long, steady precipitation• Stratus clouds• Light winds

Graphic Depiction!Graphic Depiction!

Warm FrontWarm Front

Warm FrontWarm Front

What is a cold front?• It is the leading edge of a cold air mass

How does it affect the weather?

• Higher pressure• The temperature drops rapidly• Precipitation can be heavy at the front, but

short lasting (ex. Thunderstorms, tornados, etc.)• Cumulonimbus clouds• Strong winds

Cold FrontCold Front

(Fozzy)

Cold FrontCold Front

Cold FrontCold Front

In the summer, cold fronts In the summer, cold fronts can triggercan trigger::

• thunderstorms• large hail• dangerous winds• tornadoes

Stationary FrontStationary Front

What is a stationary front?

• When a warm or cold front stops moving, it becomes a stationary front

What is humidity and how is it What is humidity and how is it measured?measured?

• Humidity is the amount of water vapor that exists in the air. The warmer the air, the more moisture can be present. Think about muggy days in August vs. Frigid days of January.

• Humidity is measured with a

• hygrometer

Clouds clipClouds clip

HOW ARE CLOUDS FORMEDHOW ARE CLOUDS FORMED

1. Water evaporates

2. Water vapor rises

3. Water vapor loses energy (cools) and condenses

4. Clouds form (clouds are actually liquid water)

CLOUD CLASSIFICATIONCLOUD CLASSIFICATION

• Cirrus-high level clouds that have bases below 7,000 feet

• Cumulus- mid-level clouds that have bases between 7000-18,000 feet

• StrausStraus-low level clouds that have bases below 6,500 feet

• Cumulonimbus-tallest of all clouds that can go up to 60,000 feet.

Cloud classification root words!Cloud classification root words!

•  

Latin Root  Translation Example

cumulus heap Fair weather cumulus

stratus Layer Altostratus

cirrus Curl of hair Cirrus

nimbus Rain Cumulonimbus

CIRRUSCIRRUS• High altitude and wispy

• Some have a wavelike appearance

• Are usually thin allowing moonlight and sun to shine through

• Associated with fair weather

CUMULUSCUMULUS

• Usually puffy

• Noticeable vertical development

• Have popcorn appearance• Can be widely scattered or clumped

• Associated with fair weather

STRATUS STRATUS warm front cloudswarm front clouds

• Lowest of the low clouds

• Appear as an overcast, but can be scattered

• Can be in layers• Associated with

long periods of rain• fog

CUMULONIMBUS CUMULONIMBUS cold front cloudscold front clouds

Can produce lightning, heavy rains, hail, strong winds, and tornados. They are the tallest of all clouds

What is weather forecastingWhat is weather forecasting

• Weather forecasting is the application of science and technology to predict the state of the atmosphere for a future time and a given location.

• Forecasts become less accurate as the difference in time between the present moment and the time for which the forecast is being made (the range of the forecast) increases. Why?

Why is weather forecasting Why is weather forecasting important?important?

• Air traffic

• Boating

• Military

• Agriculture

• Public safety

Who is responsible for Who is responsible for predicting the weather?predicting the weather?

• Meteorologists – they analyze weather data and make weather forecasts based on the data

What tools are used for weather What tools are used for weather forecasting?forecasting?

• A weather balloon measures weather high in the troposphere.

A satellite orbiting Earth takes pictures of clouds from space to help us see where and how fast clouds are moving.

A radar shoots a microwave into a cloud to shows where precipitation is falling and how much. The wave bounces back when it hits the precipitation.  It can also spot severe storms and how fast they are moving.

How is temperature measured How is temperature measured and displayed on a map?and displayed on a map?

• Thermometer measures the temperature of an air mass! The reading should be taken in the shade.

• Isotherms connect areas of equal temperatures on a map just like isobars!

Weather BalloonWeather Balloon

Weather Satellite

Doppler radar