Bio 126Bio 126Climate and WeatherClimate and Weather

Earth from the moonEarth from the moon

MeteorologyMeteorology

Climate- over all combination of temperature and precipitation that a region experiences– Mediterranean= winter precipitation

followed by long hot, dry summers Weather- daily, weekly variations in

these phenomena

Solar radiationSolar radiation

Climate zonesClimate zones

Warm at equator, cooler towards poles.– Caused by intensity of sunlight at

equator.– Poles receive less on a per area basis.

Solar radiation around the Globe

Solar radiation around the Globe

SeasonsSeasons

Caused by tilting of earth on its rotational axis.– Intensity of sunlight varies.– Most extreme at poles– Little change at equator.

Causes of SeasonsCauses of Seasons

PrecipitationPrecipitation

Varies by latitude.Wet at equator 00, and 600 N / SDry at 300, and 900 poles

– Poles are frozen desertsCaused by formation of Hadley Cells

Hadley CellsHadley Cells

Air currents in Hadley Cells caused by air density not just temperature.

Uneven heating in different regions on the earth cause winds.

Hadley CellsHadley Cells

Air rises (0, 60) due to warming of surface.

– Adiabatic Cooling as air rises as rises the air becomes less dense and cooler this cause water to condense and fall as rain, snow

Air falls (30, poles) – Adiabatic warming as air falls

air becomes compressed, and heats. air absorbs moisture, falls as dry air and absorbs

moisture from the environment.

Global air circulation, precipitation, and winds: Hadley cellsGlobal air circulation, precipitation, and winds: Hadley cells

Global Air CirculationGlobal Air Circulation

West Coast LatitudesWest Coast Latitudes

San Diego=32.5; LA= 34; Sta. Barbara= 34.5 ; Sta. Cruz=37, SF 37.75; Eureka= 40.75

Approx. Portland= 45.5; Seattle= 47.5 ; Juneau= 58; Anchorage = 61

CA large enough to span climate zones between Hadley cells.

– South dry– North wet

Seasons- Seasons-

tilting of earth moves solar equator. Effectively moves 300 dry zone

north in summer– descending dry air belt is pushed

farther north in our summer, the wet belt moves farther south

giving us wet winters

Causes of SeasonsCauses of Seasons

Prevailing windsPrevailing winds

These Hadley cell wind currents move North or South

The spinning of the earth makes it seem like they come at an angle.– In CA our winds, storms usually come

from the south west.– Rains often bring warmer weather

Ocean currentsOcean currents Prevailing winds cause ocean waters to

move in the prevailing direction. huge gyres form due to earth’s spinning

known as the Coriolus effect – In Northern Pacific clockwise general

direction of flow from our coast.– Ca. Current, with its cold, nutrient rich water

flows from Alaska southwards along our coast

– At Sta. Barbara coastline moves east, current flows due south, allowing Southern Ca. water to warm

Hadley cellsHadley cells

Barometer measures air Barometer measures air pressure pressure

Low pressure (rising air) associated with storms.

High pressure (descending air) blocks storms.

– High pressure off California in summer blocks most storms

Global Trade Wind PatternsGlobal Trade Wind Patterns

Ocean CurrentsOcean Currents

BiomesBiomes

Major vegetation types that also determine the animal community present.

Determined mostly by climate – Soil also important factor

Figure 50.3 A climograph for some major kinds of ecosystems (biomes) in Figure 50.3 A climograph for some major kinds of ecosystems (biomes) in North AmericaNorth America

BiomesBiomes

Patterns of distribution in the biospherePatterns of distribution in the biosphere

Major BiomesMajor Biomes

Coniferous forest, Lady Bird Grove (top left), Sequoias (right), rain forest Coniferous forest, Lady Bird Grove (top left), Sequoias (right), rain forest (bottom left)(bottom left)

Temperate deciduous forest, Great Smokey Mountains National ParkTemperate deciduous forest, Great Smokey Mountains National Park

Tropical forestsTropical forests

SavannaSavanna

Desert. Organ Pipe State Park (top), Joshua Tree National Park (bottom left), Death Desert. Organ Pipe State Park (top), Joshua Tree National Park (bottom left), Death Valley (bottom right)Valley (bottom right)

Temperate grassland- PrairieTemperate grassland- Prairie

Tundra. Denali National Park (left), reindeer (right)Tundra. Denali National Park (left), reindeer (right)

Rain shadow Rain shadow Precipitation increases as storms

are pushed up over mountians.– accordingly rain becomes snow

– As air moves up slope in the Sierras it cools 3-5 degrees per 1,000 ft.

This is the same effect as moving 300 miles farther north !

Causes deserts in Nevada

Most islands with mountains have wet and dry sides

RainshadowRainshadow

RainshadowRainshadow

Summer Fog Summer Fog

– Inland air warms quickly. This rising air, pulls in coastal air.

– Cold water off CA. cools incoming warm, moist ocean

– Coast causes summer fog. Essential for southern ranges of

Coast Redwoods, and relic pines, cypress species

Temperature Inversion layersTemperature Inversion layers

dense air flows downhill and collects in low spots, valleys. Great Central valley is an example.

– This dense air may be blocked by hills etc. from warmer winds which blow over the top of dense air, leaving it alone.

– Dense tule fog may form for days. Inversion layer (cold air higher up) also traps

pollutants. Mexico City problems Reno, Tahoe now ban fireplaces.

Often “burn off” in summer but leave the haze of phytochemical smog behind.