Atmosphere

atmospheric circulation

ultimately powered by the sun energy through uneven heating at Earth’s surface

heat imbalance between equatorial and polar regions

causes winds and surface currents

1. sphericity

2. seasons

Causes of uneven solar heating on Earth:
1.
2.

oceanic currents

about 1/3 of the heat redistribution from tropics to poles occurs through

atmospheric currents

about 2/3 of heat redistribution from tropics to poles occurs through

50-100km

how thick is the atmosphere?

1. temperature

2. humidity

affect air density:
1.
2.

humid air

less dense than dry air (rises faster)

air heated at Earth’s surface

rises due to its lower density and eventually cools as it expands causing water vapor

1. vertical motion

2. formation of high and low pressure

changes in air density either lead to:
1.
2. (this leads to horizontal winds)

Coriolis effect

occurs because of conservation of angular momentum; arises due to the fact that earth rotates on its axis

right, northern
left, southern

the coriolis force acts to the ____ in the _____ hemisphere and to the _____ in the ______ hemisphere

1. nitrogen

2. oxygen

3. water vapor, carbon dioxide, trace gases

what gases make up Earth’s atmosphere:
1.
2.
3. (3)

interactions between organisms and gases

why is Earth’s atmosphere hospitable to life?

1. angle of sun rays

2. earth’s tile and seasons

3. land vs water

what causes uneven heating on earth?:
1.
2.
3.

in the tropics because warm, moist air rises

where does strong vertical motion occur and why?

it increases (salt left behind)

what happens to ocean salinity when water evaporates?

heat is constantly transported from the tropics

why don’t the poles freeze solid?

the poles

where is coriolis strongest?

because of the coriolis effect

why are there 3 circulation cells instead of 1?

1. Hadley (0-30 degrees)

2. Ferrel (30-60 degrees)

3. Polar (60-90 degrees)

what are the 3 cells?:
1.
2.
3.

where trade winds meet near the equator

what is the ITCZ?

1. rising warm air

2. clouds

3. heavy rainfall

what weather occurs in the ITCZ?:
1.
2.
3.

it follows the warmest sea surface temperatures (moves with the sun)

why does the ITCZ move?

easterly winds from 0-30 degrees latitude
(NE in northern hemisphere, SE in southern hemisphere)

what are trade winds?

winds from 30-60 degrees blowing west to east

what are westerlies?

cold winds from poles moving east to west

what are polar easterlies?

1. low pressure

2. light winds

3. high rainfall

4. low salinity

characteristics of the equator:
1.
2.
3.
4.

1. high pressure

2. dry air

3. clear skies

4. high salinity

what are characteristics of subtropical highs (about 30 degrees):
1.
2.
3.
4.

monsoon

seasonal wind pattern that reverses direction

1. land vs ocean heating differences

2. seasonal movement of the sun

what causes monsoons:
1.
2.

wet summers and dry winters

what weather do monsoons cause?

sea breeze

wind from the ocean to land (daytime)

land breeze

wind from land to ocean (night)

too far inland

why doesn’t Baton Rouge experience strong sea/land breezes?

anticyclone

high pressure, sinking air, clockwise rotation (northern hemisphere)

cyclone

low pressure, rising air, counterclockwise rotation (northern hemisphere)

geostrophic wind

wind where pressure gradient force = coriolis force

above the surface

where does geostrophic flow occur?

tropical cyclones

form over warm water
powered by heat from condensation (ex: hurricane)

extratropical cyclones

form at fronts between air masses
powered by temperature differences

cold front

cold air pushes under warm air

warm front

warm air rises over cold air

rain and storms

what usually happens at fronts?

the atmosphere is unstable

why is weather hard to predict?

only a few days

how far ahead can we rely on forecast weather