1. Just how does it work? Atmospheric pressure= 14.7 psi
Air Pressure
Just how does it work? Atmospheric pressure= 14.7 psi

2. Units of measure for Pressure
2 units for measuring pressure are, millibars, and inches of Mercury
29.73
997
30.18
994

3. Which pressure gradient would result in greater wind velocity?
Isobars- iso is Greek meaning equal, bar is a unit of measuring pressure, so Isobars are lines of equal pressures

4. Things that effect Air Pressure
Altitude (Elevation)
Temperature
Humidity (moisture in the air)

5. Altitude
The higher the altitude, the lower the air pressure. (less dense)
The lower the altitude, the higher the air pressure. (more dense)

6. Draw the relationship between air pressure and air density.

7. Temperature
As the temperature goes up, the air pressure goes down. (hot molecules are further apart- less dense, less pressure).
As the temperature goes down, the air pressure goes up. ( cold air is more dense than warm air).

8. Humidity Humidity is the amount of moisture in the air.
Water vapor weighs less than air molecules.
As the air becomes more humid, the air pressure goes down (moist air weighs less than dry air).
Drier air has higher pressure because dry air weighs more than moist air, therefore it has greater pressure.

9. Winds
Cause of wind

10. Wind blows from areas of
to areas of
high
pressure
low
pressure

11. How are winds named?
The direction
from which
they come

12. What instrument is used to measure:
wind speed
air pressure
anemometer
barometer
[ORIGIN from Greek anemos ‘wind’]
[ORIGIN from Greek baros ‘weight’]

13. How wind develops
Caused by differences in air pressure, due to unequal heating of the atmosphere

14. This is because the air is Therefore, clouds CANNOT form.
In a high pressure area,
air will (rise, sink)
because the air is
(less, more) dense.
This is because the air is
(cold, warm)
and (rises, sinks).
Therefore, clouds CANNOT form.

15. This is because the air is
In a low pressure area,
air will (rise, sink)
because the air is
(less, more) dense.
This is because the air is
(cold, warm)
and (rises, sinks).
Therefore, clouds are
LIKELY to form.

16. Winds are created by…
Heating the air, decreases pressure (warm air rises creating a low pressure)
Cool air rushes in to replace the warm air (cooler dense air, produces high pressure)
Winds form, as air goes from areas of high pressure to areas of low pressure

17. Coriolis Effect Coriolis Effect Directions
Rotation of the Earth causes moving air and water to change direction
Northern Hemisphere- winds curve to the right
Southern Hemisphere- winds curve to the left

18. Correctly draw the direction of wind flow
around both a high and a low pressure area
in the NORTHERN HEMISPHERE.
Counter- clockwise Clockwise

19. counterclockwise wind direction
low pressure
high pressure
warm or cold air
air rising or sinking
clouds or no clouds
clockwise or
counterclockwise wind direction
winds toward or
away from the center
warm
cold
rising
sinking
clouds
no clouds
counter clockwise
clockwise
toward
away

20. 2 Types of Wind
1. Global
2. Local

21. Global Winds Doldrums Trade Winds Prevailing Winds Polar Easterlies
Winds that blow over large distances. Do not travel North and South due to the Coriolis Effect
4 Types of Global Winds
Doldrums
Trade Winds
Prevailing Winds
Polar Easterlies

22. Trade Winds
Trade Winds

23. Doldrums At the Equator, surface winds are calm and weak
Now known as, Intertropical Convergence Zone (ITCZ)
At the Equator, surface winds are calm and weak
Why would these winds be calm and weak? When would this cause a problem?
ITCZ

24. Trade Winds 30 degrees North and South of the Equator
Calm Winds, few clouds, little rain fall
Warm air rising from the equator cools and sinks
Also known as the Horse Latitudes

25. Prevailing Westerlies
Strong Winds
Located in the belt degrees latitude in both Hemispheres
Has an impact on the US weather
Is the prevailing wind in the United States

26. Polar Easterlies Cold, but weak winds Near the North and South Poles
US weather is influenced by these
Cooling takes place between the degree latitude as it approaches the poles

27. Jet Stream Discovered in the 1940’s
Can be found in the upper Troposphere
Strong, high speed and high pressure
Moves West to East across the US, moving storms

28. Local Winds Cover short distances and blow from any direction
2 Types of Local Winds
Sea Breezes- from sea to land
Land Breezes- from land to sea

29. Sea Breeze

30. Land Breeze