test 2 review atmosphere

Why is air pressure, High & lows. Why distinctive
pattern

Pressure belt

What causes wind to converge at equator to be deflected to west?

High pressure belt at subtropical high and low pressure belt due to Coriolus deflection and earth’s rotation

Under conditions of constant
pressure, relationship between
temperature and gas volume

Temperature increases gas volume
increases.

Under conditions of constant gas
volume, relationship between
temperature and pressure

Temperature increases gas
pressure increases

In adiabatic process, cooling through:

expansion of air

In adiabatic process, heating through:

compression of air

“average” pressure (sea level)

1012 mb

How is Pressure Measured?

barometer

What is Pressure Measured in?

bars and pascals

Sparsely distributed isobar represents

Gentle wind

Closely spaced isobar represents

Strong wind

Isotherm

same temperature line

Isobar

Same pressure line

Factors cause air pressure to change

Altitude
➢Elevation
➢Temperature
➢Earth rotational force ( global air
circulations)
➢Regional air circulations

Influences on Wind Direction

1. pressure gradient
2. friction
3. Coriolis force

pressure gradient

driven by unequal heating of the Earth’s surface

High pressure

Cold air is heavy
Sinks
High pressure prevails
Low moisture contents
Dry air expected
No precipitation
Calm weather

Low pressure

Warm air is lighter
Rises
Low pressure prevails
High moisture contents
Moist air expected
Precipitation Possible
Windy, violent weather

Influences on Wind Direction

Friction decrease as altitude
increase and wind become faster

Coriolis force

a rightward deflection of wind in the
Northern Hemisphere

Cyclone

Low Pressure
• Direction of wind anticlockwise
• Air rising or moves upward
• Creates convergent wind circulation
• Counterclockwise convergent in the northern
hemisphere
• Clockwise convergent in the Southern hemisphere

Anticyclone :

High Pressure
Direction of wind clockwise
Air descends toward the surface
Creates a divergent wind circulation
Clockwise divergent in the northern hemisphere
Counterclockwise divergent in the southern hemisphere

Anticyclone Clockwise

divergent in the northern hemisphere

Anticyclone counterclockwise

divergent in the southern hemisphere

Cyclone Clockwise

convergent in the Southern hemisphere

Cyclone counterclockwise

convergent in the northern hemisphere

Which of the following circulation patterns is characteristic
of a cyclone or low pressure in the Southern Hemisphere?

air flowing inward, clockwise

Which of the following circulation patterns is characteristic
of a cyclone or low pressure in the Northern Hemisphere?

air flowing inward, counterclockwise

Which of the following circulation patterns is characteristic
of an anticyclone or high pressure in the Southern
Hemisphere?

air flowing outward, counterclockwise

Which of the following circulation patterns is characteristic
of an anticyclone or high pressure in the Northern
Hemisphere?

air flowing outward, clockwise

When viewed from below the North Pole, the polar easterlies

flow clockwise around the pole

When viewed from below the South Pole, the polar
easterlies

flow counterclockwise around the pole

More and more wind deflection occurs with height because

friction decreases with height and deflection by the
Coriolis effect increases with wind speed

ITCZ

Equatorial Low

Trade Winds, Northeast winds

Subtropical high to equatorial low

Trade winds, South east winds

Subtropical high to equatorial low

The Hadley cell
is characterized by

low pressure with rising air over the equator, and high pressure with sinking air at 30° N and 30° S (subtrop high to equatorial low)

The Ferrel cell
is characterized by

low pressure with rising air over the subpolar low, and high pressure with sinking air at 30° N and 30° S (subtropical high to subpolar low)

The Polar cell
is characterized by

high pressure with sinking air over the subpolar low, and low pressure with rising air at 90° N and 90° S. (polar high to subpolar low)

In the Northern Hemisphere, the westerlies are created by
the Coriolis effect acting on air

from the subtropical high flowing north to the
subpolar low.

To create a land breeze

the cool air over the land sinks, creating high
pressure. Warm air over water rises, creating low pressure. This
creates an offshore breeze

To create a Sea breeze

the warm air over the land rises, creating low
pressure. Cool air over water sinks, creating high pressure.
This creates an onshore breeze