Air Pressure and Wind
 Air Pressure: the amount that air presses or pushes on
anything
 You usually do not notice air pressure, but you do
notice its effects
 As you travel higher above the earth, the air pressure
changes
 Higher=Less Pressure
 Temperature also changes the
higher you travel.
 The Earth’s surface heats the air.
 Farther From Earth = Cooler
Temperature
Temperature:
34ºF
Temperature:
54ºF
Temperature:
76ºF
Low Air Pressure
 As the air near the surface of the earth becomes
warmer, the air particles move farther apart.
 The air become lighter and rises
 This is when a low-pressure area forms
High Air Pressure
 Cole air s heavier than warm air.
 It’s air particles are packed closer together and push
down harder.
 This is when a high-pressure area forms.
Wind
 Air moves from a place
with high pressure to a
place with low pressure.
 Air moving is called wind.
 When the cooler air from a
high-pressure area sinks
toward the earth, it causes
wind.
 That’s why you will feel a
cool breeze…even on a
warm, summer day.
Measuring Air Pressure
 Barometer
Measuring Wind Direction
 Wind Vane
Measuring Wind Speed
 Anemometer
Let’s Review!
What causes wind?
Wind is caused by air moving from a
high-pressure area to a low-pressure
area.
How is air pressure measured?
Air pressure is measured by a
barometer.
 How do scientists measure wind
direction?
Scientists measure wind direction with a
wind vane.
 How do scientists measure wind speed?
Scientists measure wind speed with an anemometer.