CH 15 – Air, Weather, Climate Pages: 323 – 329; 330-344 + Inconvenient Truth

Patterns?

F. 50.18

Weather or Climate? Weather: short-term atmospheric events at a specific locality Climate:

Weather: short-term atmospheric events at a specific locality Climate: long-term patterns of weather over broad regions

Weather and climate in middle GA?

Weather and climate in middle GA? warm, humid summers (thunderstorms) long growing season mild winters rainfall - winter

The sun is the climate engine

Infrared radiation derived from sunlight is the climate engine

Weather and Climate the result of solar radiation ambient temperature

Weather and Climate the result of solar radiation ambient temperature Moisture (evaporation and transpiration) Wind (transfer of mass between low and high pressures)

Basic atmospheric structure Stratosphere – 50-80 km Troposphere – 0-10 km Basic atmospheric structure

Structure of atmosphere limited water vapor Weather and Climate constrained by atmosphere

Structure of atmosphere

4 principles of Climate curvature tilt

A hypothetical continent

4 principles of Climate 1. The sun heats unevenly. curvature tilt

Solar Radiation heats the earth (unevenly) Sun’s rays Atmosphere Large surface area 40% insolation at poles compared to tropics Small surface area Equator Earth

angle of sunlight UNlabeled Consider the Equinox solar equator = latitudinal equator

40 Clouds and rainfall keep temperature uniform across the tropics 30 20 10 Mean annual temperature °C -10 -20 10 20 30 40 50 60 70 80 Degrees latitude

The angle of the earth’s axis is responsible for seasonal variations on the earth.

angle of sunlight UNlabeled Consider the Equinox solar equator = latitudinal equator

22 September 21 March

21 June

21 December

Solar equator shifts N and S influencing rainfall

Solar Equator Heated air rises, cools, releases rain

Relationship between solar energy and rainfall? relative humidity

relative humidity Water evaporates heated, moisture-laden air rises

relative humidity air pressure and temperature drop rising air expands and cools

relative humidity Relationship between solar energy and rainfall? 5. Condensation begins (moisture holding capacity decreases) 6. precipitation may result

Solar Equator Heated air rises, cools, releases rain Low pressure at surface (Tropical Lows) surface air moves in from North and South

30 N & S of solar equator Cooled air sinks, warms, ‘holds more’ moisture

30 N & S of solar equator Cooled air sinks, warms, picks up moisture High pressure at surface deserts in the Horse Latitudes

development of a Hadley cell

all three hadley flow and winds

1. Solar Radiation heats the earth (unevenly) latitudinal gradients in temperature Hadley cells determine distribution of rainfall and pressure tropical lows, subtropical highs Major forest types and deserts

Biomes

2. The Earth Spins Speed at North Pole? Equator?

The Earth spins ‘The Coriolis Effect’ Predominant Winds Tropical easterlies (0-30º) Temperate westerlies (30º-60º)

Hurricane Season ITCZ

Climate 3. Wind pushes water creating gyres

Wind pushes Water Nova Scotia - England Ocean currents distribute energy and modify coastal climates

Driest deserts in the world lie on the west coasts of continents

Annual World Precipitation

Regional Climatic Influences Topography and Geography modify patterns generated by principles 1-3

Regional Climatic Influences Topography and Geography modify pattterns generated by principles 1-3 a. The Rain Shadow Effect b. Altitudinal Effects c. Continental effects (oceans mediate extremes)

Regional Climatic Influences Pacific NW – Olympic and Cascade mtn ranges The Rain Shadow Effect

Temperate “Rainforests”

Eastern Oregon dry grasslands

e.g. rain shadow in N. A. North American Deserts

Regional Climatic Influences Topography and Geography modify pattterns generated by principles 1-3 a. The Rain Shadow Effect b. Altitudinal Effects c. Continental effects (oceans mediate extremes)

Altitudinal Effects e.g., Cloud Forest biome of Trinidad

Altitudinal Effects Even a few hundred meters can significantly alter community type.

year-round 100% humidity

Regional Climatic Influences Topography and Geography modify pattterns generated by principles 1-3 a. The Rain Shadow Effect b. Altitudinal Effects c. Continental effects (interiors experience temperature extremes)

Variation in Climate Determines distribution of large scale assemblages of organisms

A hypothetical continent