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