the atmosphere (ch. 1)myslu.stlawu.edu/~aodo/slu/climate/assignments/e1_review_15.pdf · the top of...

Envs, Geol, Phys 112: Global Climate Exam 1 Review

Energy-Atmosphere System Review Aguado & Bert, Ch. 1, 2, 3, 4, 5, 8

Location on Earth Latitude & Longitude great circles, prime meridian, time zones, cardinal points, azimuth Geography provinces, states, nations major physical features The Atmosphere (Ch. 1) Structure Compositional structure Homosphere (mixed and homogeneous) Heterosphere (heavy atoms sink to bottom) Thermal structure Troposphere, Stratosphere, Mesosphere, Thermosphere Functional structure Ozonosphere Ionosphere Composition Primarily N2 (78%), O2 (21%), Ar (1%) Differs from Mars, Venus Evolution of composition Oceans absorbed CO2, locked it into rocks Life generated and maintains oxygen levels

Stromatolites in Shark Bay, Australia

Envs, Geol, Phys 112: Global Climate Spring 2015

Sun and Earth (Ch. 2) Energy from the sun solar wind EM radiation Seasons Equinoxes & Solstices Named latitudes Equator, Tropics, Arctic & Antarctic Circles What are their latitudes How are they defined? Energy Balance & Temperatures (Ch. 3) Insolation Solar constant: amount of energy reaching the top of Earth’s atmosphere 1,370 W/m2 about 51% reaches ground ( ~700 W/m2) Reflection Albedo: Earth ~ 31, Moon ~8 Scattering Blue sky & Daylight Light is scattered IR is not scattered … so IR comes only in sunbeam making sunbeam feel warm Absorption by atmosphere Transparent to visible, some IR, radio Absorbs most IR, almost all UV, X-ray Absorption & Re-radiation by surface (Greenhouse) Absorbs shortwave (visible), radiates longwave (IR) Heat Capacity: Energy required to raise (or lower) the temperature of a substance Latent heat: Heat released or absorbed when something (water) changes state released: gas to liquid (condensation), liquid to solid (freezing) absorbed: solid to liquid (melting) or liquid to gas (evaporating) Heat transfer Conduction: Hot stuff heats neighbors (inefficient!) Convection & Advection: Hot stuff moves Radiation: Heat, itself moves


Energy at Earth’s Surface Diurnal variation Daytime heating: incoming energy exceeds radiated energy T increases… Ground heats faster than air, so air near ground is hottest. Nighttime cooling: outgoing radiation exceeds incoming sunlight, T falls… Ground radiates more efficiently than air, so air near ground is coldest. Seasonal variation Tropical Energy Surplus Polar Energy Deficit Controls on Temperature Temperature scales C = ((5/9) (F – 32) F = (9/5)C + 32 K = C + 273.15 Insolation Variation With Latitude & Season (sun angle!) Equator, Tropics of Cancer & Capricorn, Arctic & Antarctic Circles Tropics, Temperate Zones, Polar Zones With Altitude Normal Lapse Rate = 6.4 C°/km Water Humidity: humid air has higher heat capacity than dry air Clouds reflect sunlight into space Water vapor absorbs infrared radiation, so cooling earth warms the moist air Moist ground conducts heat away from surface, keeping ground surface cooler Lakes and oceans heat and cool much more slowly than land


Atmospheric Pressure and Winds (Ch. 4) ATMOSPHERIC PRESSURE Pressure -- weight of column of air (1 hPa = 10 Newtons/meter2 = 1 mb) Pressure depends on Density of air (cold air more dense than warm) Height of air column (varies with latitude)

WIND Air is Moved by Forces Pressure Gradient Force (FPG) F = P/d P is the change in pressure over distance d Coriolis Force (FC) Only affects MOVING air … goes away in still (or very slow) air Friction Friction with Earth's surface slows wind No friction aloft Geostrophic Winds (aloft) occur when FPG = FC parallel to isobars Clockwise around highs in N. Hemisphere Counterclockwise around lows in N. Hemisphere Non-Geostrophic Winds (surface) occur when FPG ≠ FC force because of wind friction with surface inward to low, outward from high

Regional Winds: 1. Land & Sea Breezes Sea Breeze: (day) Insolation heats land, air rises, cooler air blows in from the sea. Land Breeze: (night) Water cools more slowly than land, air rises, cooler air blows from land. 2. Up & Down Valley Breezes Up-Valley Breeze: (day) Insolation heats air, air rises up mountain side. Down-Valley Breeze: (night) Air in contact with mountain surface cools, sinks down the valley. 3. Katabatic Winds Prevailing winds descend mountains (Chinook, Föen, etc.) High pressure forces winds over mountains (Santa Ana) 4. Monsoons Seasonal shifts in location of high and low pressure systems Asian Monsoon and North American Monsoon


mass of water vapor (grams)mass of air (kg)

Specific HumidityMaximum at Current Temp.

3C

kgPressure (Pa)m287 T 273

Atmospheric Moisture (Ch. 5) 1) Water on Earth 71% of surface area: Pacific Ocean and Southern Hemisphere Forms 97% Oceans 3% Freshwater … of this 22% Groundwater 78% Surface water … of this 99% in glaciers! 2) Properties Polar Molecule (Mickey Mouse) Creates surface tension Makes solid float in liquid Enables capillary action Creates hexagonal crystals Pencil slices create halos, sun dogs, sun pillars, etc. 3) Indices of Water Vapor Content Psychrometric Charts! Specific Humidity Relative Humidity Air Density (dry air) Moisture Content

Positive side where electrons rarely hang out

Negative side where electrons mostly hang out

3 3 3

kg Dry Airkg Dry Air m Dry Air m Dry Air m Dry Air

g water g water m water____ ____

Review the “Measuring Humidity” worksheet!


Cloud Development and Forms (Ch. 6) 1) Review air lifting mechanisms a) Convergent lifting b) Convectional lifting c) Orographic lifting d) Frontal lifting 2) Lapse Rates a) Environmental lapse rate -environment’s change in temperature with height b) Dry adiabatic lapse rate - change in temperature with height of a dry parcel of air - dry parcels cool more quickly than moist parcels c) Moist adiabatic lapse rate - change in temperature with height of a parcel in which water is condensing - moist parcels are heated by latent heat so they cool more slowly than dry 3) Atmospheric Stability a) Stable conditions: parcel always cooler than environment - environmental lapse rate steeper (slower) than adiabatic rates b) Unstable conditions: parcel always warmer than environment - environmental lapse rate less steep (faster) than adiabatic rates c) Conditionally stable conditions: - dry air cools faster than surroundings, - moist air cools more slowly than surroundings 4) Clouds a) Forms Cumulo: “Heaps” Strato: “Layers” b) Heights: Cirro: High, Alto: Middle, No prefix: Low


Global Scale (Hadley) Atmospheric Circulation (Ch. 8) DRIVEN BY SUNLIGHT HEATING SURFACE AIR AT SUBSOLAR LATITUDE 1. Air rises at ITCZ Rising Air = Low Pressure Cools -- moisture condenses -- precipitation Spreads north and south aloft and continues cooling 2. Air sinks at about 30 N and S (STHPC) Sinking Air = High Pressure Dry since it lost moisture when rising Spreads north and south, Coriolis deflection creates Trade Winds & Westerlies 3. Air Sinks at Poles (Polar High) Moves southward (northward) & deflects right (left) along surface Polar Easterlies 4. Convergence Zone at 60 N and S (Polar Front) Rising Air = Low Pressure Cools -- moisture condenses -- precipitation Spreads north and south aloft and continues cooling

BE ABLE TO

RECREATE THIS

DIAGRAM

WITH NO HINTS!

WHERE ARE THE

ITCZ, RAINFORESTS, DESERTS, TRADES, WESTERLIES, AND

EASTERLIES?

WHY ARE THEY

WHERE THEY ARE?


Lifting (Section 6.1) Forced orographic Where does this happen? What’s the result? frontal (know characteristic weather & cloud patterns) convergent lifting convectional lifting Air Masses and Fronts (Ch. 9) Air Masses Large volumes of air Move and collide Fronts form at collision zones Most weather takes place at fronts


Weather associated with a cold front:

Weather Phenomenon Before Front Passage Contact with Front After Front Passage

Temperature Warm Sudden Cooling Cold & Getting Colder

Pressure Steady Decrease Level then Increasing Steady Increase

Clouds Cirrus, Cirrostratus Cumulus & Cumulonimbus Cumulus then Clearing

Precipitation Showers Heavy Precip., T-Storms Showers then Clearing

Weather associated with a warm front:

Weather Phenomenon Before Front Passage Contact with Front After Front Passage

Temperature Cool Sudden Warming Warmer then Leveling

Off

Pressure Steady Decrease Level Slight Rise Then Decrease

Clouds Cirrus, Cirrostratus,

Altostratus, Nimbostratus

Stratus, Cumulonimbus sometimes Clearing with stratus

Precipitation Showers, snow, sleet

or drizzle Drizzle None


Mid-Latitude Cyclones (Ch. 10) Warm and cold air masses pushing on each other Instability forces a wave to start, then rotation follows Cold front moves faster than warm front Cold front overtakes warm, pushes warm air aloft Occluded front! Inversion remains after dissipation of occlusion Dry Lines Separate air masses at same temperature (eg. cT next to mT in Texas) Humidity differs on either side

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