Topic: What is Wind? PSSA: 3.5.7.C / S8.D.2.1
Objective: TLW explain the relationship between air pressure and wind direction. TLW identify factors that affect wind movement.
MI #1: What is Wind? Wind is the movement of air caused by differences in air pressure. Air moves from areas of high pressure to areas of low pressure. The greater the pressure difference, the higher the wind speed. Winds are described by the direction from which they are blowing, therefore an east wind blows from the east.
MI #2: Global Pressure Differences Differences in air pressure are caused by unequal heating of the air. Air near the equator gets more direct sunlight and therefore is warmer, so it rises, creating low pressure. Cold air at the poles sinks, creating denser, high pressure air which flows toward the equator.
MI #3: Global Pressure Belts Air moves in large circular patterns that are separated by pressure belts about every 30 degrees latitude. Low pressure is found at the equator and at 60 latitude (north and south). High pressure is found at the poles and at about 30 degrees latitude (north and south). These pressure belts help determine global wind patterns.
MI #4: Coriolis Effect The apparent curving of the global winds due to the Earth’s rotation is called the Coriolis Effect. Winds do not travel directly north or south due the rotation of the Earth. In the Northern Hemisphere winds that travel north curve to the east and winds travel to the south curve to the west.
MI #5 What are Global Winds? The combination of convection cells every 30 degrees latitude and the Coriolis Effect produce patterns of air circulation called global winds. Global winds are responsible for large scale movement of air masses which create changes in weather.
MI #6: What are Local Winds? Local winds move short distances and can blow from any direction. Local winds are caused by temperature differences created by differences in local geography.
So What…? Real Life Application Understanding wind allows us to understand why weather systems move the way they do.