circulation of the atmosphere

small and large scale circulation

microscale

mesoscale

macroscale

microscale winds

circulation is small and chaotic. can last from seconds to minutes. Hyperlocal. can be simple gusts, downdrafts, n small cortices.

mesoscale winds

Last from minutes to hours. local. some mesoscale winds (thunderstorms and tornadoes) also have a strong vertical component.

macroscale winds

These winds are the longest wind patterns. Planetary-scale patterns can remain unchanged for weeks at a time. global. 

synoptic scale

smaller macroscale circulation. Smaller macroscale systems are tropical storms and hurricanes.

land and sea breezes

form in coastal locations in the tropics and midlatitudes. Arise from differential heating of the land n water. 

sea breeze

a local wind that blows from the sea toward the land during the afternoon in coastal areas. local wind that blows from the sea toward the land during the afternoon n coastal areas. h in sky over land. low over and close to land. h close and over ocean. l high and over ocean

land breezes

local winds that blow from the land towards the sea during the nt in coastal areas. l high over land, h close n over land. l close n over ocean, h high over ocean

mountain n valley breezes

results from differential heating of mountain slopes versus valley floors

valley breezes

daily upslope winds commonly encountered in a mountain valley. start in valley floor and move up mountain slope. cool air sinks, warm air rises.

mountain breezes

nightly downslope winds commonly encountered in mountain valleys. start on mountain slopes and winds move into the valley. cold air sinks, pushing warm air up.

chinook winds

warm dry winds that move down leeward slopes of mountains. Bring drastic changes in temp. will melt slope cover rapidly, causes them to be called snow eaters. Similar winds called foehns in europe.

santa ana winds

chinook winds, in southern cali and northwest mexico. occur in fall n winter. fan regional wildfires, occur yearly. 2003, 2024-2025 rough years. dry summers and strong santa ana winds have created wildfire conditions for millennia. Movement of humans into fire prone regions and fire prevention making problem worse.

katabatic (fall) winds

originate when cold, dense air begins to move.

country breezes

mesoscale winds. caused by uneven heating of urban n country areas. results in flow from country to urban areas.

hadley model

hadley proposed that the contrast in temp between the poles n equator creates a large convection cell in both northern n southern hemispheres. assuming a featureless earth, making it wrong.

three cell circulation model

proposed in the 1920s. Warm air rises at the equator (Hadley cell). As the flow moves polewards, it begins to cool and sink at 20-35 degrees latitude. trade winds meet at the equator, in a region with a weak pressure gradient called the doldrums. The westerly circulation of surface winds (prevailing westerlies) between 30-60 degrees latitude is called the Ferrel cell. Circulation at 60-90 degrees within a polar cell produces polar easterlies. Surface flows that move towards the equator.

main levels in global circulation model

equatorial low, subtropical high, subpolar low, polar high.

three types of cells

hadley cell, ferrel cell, polar cell

idealized zonal pressure belts

equatorial low is an intertropical convergence zone (ITCZ)

subtropical highs (sth)

high pressure zones in the belts about 20-35 degree latitude on either side of the equator.

where the polar easterlies originate

polar highs near the earths poles

monsoon

seasonal reversal of winds. RAIN NOT INVOLVED!! the Asian monsoon affecting India and it’s surrounding areas (China, Korea, Japan) north American monsoon occurs in the south western U.S. and northwestern Mexico. (this monsoon is driven by extreme temps, generating a low pressure center over Arizona and results in a circulation patter that brings moist air from the gulf of cali and the gulf of Mexico to a lesser degree)

waves in westerlies

westerlies flow in wavy paths that have long wavelengths.

Rossby waves

longest known wave patterns. consist of 4-6 waves that encircle the globe. Can have a large impact on weather.

jet streams

occurs near the top of the troposphere. embedded in the westerlies. widths vary from less than 100 km to more than 500 fm. speeds can attain 100-400 kph. polar n subtropical.

Polar jet stream

occurs along a major frontal zone, the polar front. Moves faster and occasionally moves north-south during the winter.

Hadley cells are

somewhat meridional (north-south)

most other latitudes the

flow is zonal (west-east)

transfer of heat by winds and ocean currents

equalizes the latitudinal energy imbalences

ocean water movements account for

¼ of this heat transport, and winds account for remaining 3/4

the Coriolis force deflects

currents poleward, which form nearly circular patterns of ocean currents called Gyres

gulf stream

strengthened by westerly winds n continues northeastward, off coast of europe.

warm ocean currents

west side of ocean/east side of continents

cold ocean currents

west side of continents/east side of ocean 

poleward moving, [warm ocean currents moderate

high latitudes, during winter

cold currents exert

their greatest influence in the tropics n during the summer in he mid-latitudes

cold currents increase

aridity in tropical deserts along the west coasts of continents

ocean currents

have important on climate. helps maintain the earths heat balance.

cold currents offshore

result in dry current

warm offshore current

produce moist climate

upwelling

Wind-induced vertical movement is the rising of cold water from deeper layers to replace warmer surface water. Occurs where the wind blows parallel to the coast toward the equator. rising of cold water from deeper layers to warmer surface waters. brings up little critters for fish to eat. Great for fishing.

El nino

gradual warming of eastern pacific waters in dec or jan abnormal sea-surface warming occurs at irregular intervals of 2-7 yeas. usually persists for 9 months-2 years.

El nino impact

noted for its potentially catastrophic impact on weather and economies of Chile, Peru, Australia, and other countries. Arid areas can receive a lot of precipitation. A change in surface  water temp can kill fish. part of the global atmospheric circulation pattern

La nina

opposite of el nino n refers to colder than normal ocean temps.

impact of la nina

in the wester pacific, wetter than normal conditions occur. there are also more frequent hurricanes in Atlantic. past of global atmospheric circulation phenomenon. 

southern oscillation

seesaw pattern of atmospheric pressure between the eastern and western pacific. winds are the link between pressure changes and the ocean warming and cooling associated with el nino and la nina

teleconnection

the link between the weather occurring in widely separated regions of the globe

air temp causes

latitudinal variation in precipitation

distribution of land and water

complicates precipitation pattern

large landmasses in the middle latitudes

commonly have decreased precipitation toward their intiriors. interiors