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Local Winds
Reid Pierce Lincoln Jr. High Bentonville, AR
Cold, Dry, More
Dense, Air Sinks
Low Pressure
High Pressure
Ground is heated by radiation
Local Winds
Warm, Moist, Less Dense,
Air Rises
Wind
Wind – horizontal movement of air from an area of high pressure to an area of low pressure (winds are caused by differences in air pressure)
Wind Chill – the increased cooling that wind causes
William Beaufort and the Wind-Force Scale
Francis Beaufort left his home country of Ireland and began sailing at the age of thirteen. He began as a cabin boy and, within 10 years, had risen to the rank of lieutenant in the British Navy. During this time, he was aboard a ship that shipwrecked. Beaufort, and the crew with whom he worked, were stranded and became dangerously close to starving. Luckily, they were rescued before it was too late. This experience compelled Beaufort to develop improved methods for determining wind speed and ship navigation. In 1806, when he was in his 20s, he developed a scale to record daily wind speed based on the size of waves and the moving sails of ships that he could observe while at sea. In 1836, the British Navy decided that all ships would use Beaufort’s method for ranking wind speed. In the 1920s, a British meteorologist adapted the scale to land-based observations, such as the movement of leaves on trees or a flag on a flagpole.
Wind Wind Vane – instrument used to measure
wind direction
Anemometer – instrument used to measure wind speed
The Earth is heated unevenly
Global Winds
Reid Pierce Lincoln Jr. High Bentonville, AR
The Earth is heated unevenly
Coriolis Effect
Coriolis Effect - Earth’s rotation causes winds to curve - it is weaker at the equator
Convection Currents
Global Convection Currents
The Earth is heated unevenly
Global Winds
Jet stream – a current of fast moving air in the troposphere
Jet Stream – Read about Jet Stream on pg 52
Quick Quiz
Wind is the horizontal movement of air from an area of _____ pressure
to an area of _____ pressure.
A. low , high
B. high , low
C. low , no
D. no , high
2. What causes local winds?
A. High pressure systems
B. Low pressure systems
C. Differences in air pressure
D. The spinning of the earth
3. What is wind speed measured with?
A. Anemometer
B. Wind Vane
C. Psychrometer
D. Barometer
4. What is wind direction measured with?
A. Anemometer
B. Wind Vane
C. Psychrometer
D. Barometer
5. The increased cooling that winds can cause is called what?
A. Coriolis effect
B. Evaporative cooling
C. Convection currents
D. Wind chill
6. Why do winds on Earth curve?
A. Cooler air is more dense
B. The Earth spins on its axis
C. Warm air rises and cools
D. Water vapor condenses onto particles.
7. Which direction does weather typically move across the U.S.?
A. West to East
B. East to West
C. North to South
D. South to North
8. What is the current of fast moving air in the troposphere?
A. Convection Currents
B. Jet Stream
C. Sea Breezes
D. Wind Chill
