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

Earth and Atmosphere Review

Location on Earth (L1) Latitude & Longitude great circles, prime meridian, cardinal points, azimuth know the named latitudes numerical latitude (what’s at 23.5°?) why each warrants a name! Sun and Earth (L1, JS Global Weather: Introduction) Energy from the Sun (JS The Atmosphere: Energy Balance) Light = Shortwave Radiation from Sun Seasons (JS Global Weather: Introduction) Equinoxes & Solstices Named latitudes Equator, Tropics, Arctic & Antarctic Circles ⇒ Understand “Named Laitudes”

Arctic Circle, 66.5° N

Antarctic Circle, 66.5° S

Tropic of Cancer, 23.5° N

Tropic of Capricorn, 23.5° S

Equator, 0°

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Global (Hadley) Atmospheric Circulation (L9, JS Global Weather: Global Circulation, Jet Stream, Tropical Weather: ITCZ) 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 Air moving toward equator creates 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, cooling ⇒ Understand “Global Circulation Model”

Be able to draw and explain this diagram … rising & subsiding air

(pressure zones) and wind zones

(westerlies, easterlies)

ITCZ

ST High

Polar Front

Polar Front

Polar High

Polar High

Westerlies

Westerlies

NE Trades

SE Trades

Polar easterlies

Polar easterlies

90°N

60°S

30°S

30°N

60°N

0°

ST High

90°S

ITCZ

STH

STH

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a) Stationary Front

b) Cyclone begins with wave c) Mature Cyclone … cold front chasing warm front

Air Masses and Fronts (L11, JS Synoptic Meteorolgy: Air Masses) Air Masses Large volumes of air Move and collide Fronts form at collision zones Most weather takes place at fronts Dry lines separate air masses of same temperature but different humidities (e.g. cT & mT) Mid-Latitude Cyclones (L12, JS Synoptic Meteorology: Cyclone Model) Stationary front where warm and cold air masses push 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

1. Cold 2. Warm 3. Stationary 4. Occluded 5. Trough 6. Squall Line 7. Dry Line

d) Occlusion begins e) Mature Occlusion: warm air aloft (inversion)

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Fronts (L11, JS Synoptic Meteorolgy: Air Masses) … what air masses are involved? 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

Wind South, Southwest --------- North, Northwest

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

Pressure Steady Decrease Level Slight Rise Then Decrease

Wind North, Northeast --------- South, Southwest

Precipitation Showers, snow, sleet

or drizzle Drizzle or Rain None

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Atmospheric Pressure and Winds (L6, JS The Atmosphere: Air Pressure) ATMOSPHERIC PRESSURE (L6, JS Air Pressure) Pressure -- weight of column of air (1 hPa = 10 Newtons/meter2 = 1 mb) Sea-Level Pressure Standard = 1,013 hPa = 29.92 inHg WIND (L6, JS Synoptic Meteorology: 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 deflects 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 due to wind friction with surface inward to low, outward from high Lifting (L11, JS Thunderstorms: Ingredients) Forced orographic (over mountains) Where does this happen? What’s the result? frontal (know characteristic weather on prev. page) convergent lifting convectional lifting

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Positive side where electrons rarely hang out

Negative side where electrons mostly hang out

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

=

Specific HumidityMaximum at Current Temp.

=

( )( )Dry Air 3C

kgPressure (Pa)m287 T 273

=+

ρamount of water stays the same,

amount air can hold changes

Atmospheric Moisture (L13, L14) 71% of surface area: Pacific Ocean and Southern Hemisphere 97% Oceans 3% Freshwater Properties: Polar Molecule (Mickey Mouse) Creates surface tension Makes solid float in liquid Creates hexagonal crystals: Pencil slices that create halos, sun dogs, sun pillars, etc. High Heat Capacity: Energy transfer to change temperature Energy to heat 1 kg 1 C° = Energy to lift 1 kg ¼ mile! High Latent Heat: Energy transfer to change phase Energy to melt 1 kg of ice to water (at 0°C) = Energy to lift 1 kg 20.7 miles! ⇒ Understand “Stone Soup” & “Fire & Ice”! Water Vapor Content (L2) Psychrometric Charts! (L2) Specific Humidity Relative Humidity (% of moisture air can hold) Air Density (dry air) Moisture Content ⇒ Understand “Measuring Humidity”

3 3 3

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

g water g water m water____ ____

× = =

Energy Transfer and Temperature Specific Heat: Energy required per kg to raise (or lower) the temperature of substance Latent heat: Heat released or absorbed/kg when something (water) changes state released: gas to liquid (condensation), liquid to solid (freezing), absorbed: solid to liquid (melting) or liquid to gas (evaporating)

amount of water present in air

% of water air can hold

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Atmospheric Stability (L14, JS Upper Air: The Parcel Theory, Stability/Instability) 1) Lapse Rates a) Environmental lapse rate (ELR) -environment’s change in temperature with height b) Dry adiabatic lapse rate (DAR) - change in temperature with height of a dry parcel of air - dry parcels cool more quickly than moist parcels c) Moist adiabatic lapse rate (MAR) - change in temperature with height of a parcel in which water is condensing - moist parcels heated by latent heat & have higher heat capacity ⇒ cool more slowly than dry 2) Atmospheric Stability (AB7 pp. 165-174, L14) 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