Air Pressure and Winds

Triple A ProductionsArnold RobertsAllison CouchAmy Jacobs

Pressure Gradient Force

Pressure differences existing between areas cause air to blow from an area of high pressure

toward an area of low pressure

Heavy air stays close to the Earth’s surface Winds are produced Warm air is moved in an upward motion

Balancing Pressure Differences

Heavy AirHigh Pressure Zone

Low Pressure Zone

Wind

Warm Air

If distance between high and low are short1. pressure gradient is steep2. wind velocities are great

If gentle air movements occur when zones are far apart

1. the degree of difference is not great

Differences in Pressure Zones

Convection System

The circulatory motion of descending cool air and ascending warm air

The Coriolis EffectAs winds move from high pressure to low

pressure:winds in the N. Hemisphere tend to travel to the

right,winds in the S. Hemisphere tend to travel to the

left

Coriolis Effect

The skaters in the middle of the circle do not need to move very quickly, while the out most skaters have to move rapidly to maintain this line

The Earth rotates on its axis

Equatorial regions are rotating much faster

Polar regions are rotating much slower

How does this relate?

When together they produce spirals rather then straight lines of wind

The spiral is the basic form of many storms

Coriolis Effect with Pressure Gradient Force

The Frictional Effect

The cause of wind to follow an intermediate path

Movements are slowed due to friction on Earth’s surface

Friction becomes ineffective about 1 mile above the Earth’s surface

Friction causes wind speed to decrease and change direction

Wind

Global Air Circulation

cosscience1.pbworks.com

Equatorial Low Pressure• Areas of low pressure at the equator line

Subtropical High Pressure• Cooled heavier air from the equatorial air

pressure

Northeast Trades and Westerlies (Southwesterlies)• Belts of wind caused by the cooled air

reaching the earths surface

Polar Air Pressure• Subpolar low is ascending air north of the

westerlies• Polar Easterlies connect the Subpolar low

to the Polar high pressure• Has the greatest effect on Jet Streams

Jet Streams• Strongest flows of upper air wind

• 30,000 – 40,0000 feet from the earths surface

• Air travels East to West, in both hemispheres, at 100 – 200 MPH

• Tends to separate cold polar air from warm tropical air

• Movement of the Jet Stream has the greatest effect on monsoon season in Southeast Asia

Monsoons• Monsoon wind changes directions seasonally

• Sothern and Eastern Asia is effected by this phenomena the most