1. Pressure and Wind

3. Impact of Temperature on Air Pressure
Warm air is less dense than cold air. Therefore, warm air has a lower air pressure and cold air has a higher air pressure.
The molecules in warm air are moving fast and are spread farther apart. Therefore there are fewer air molecules in a given area to push down on you.
Warm
Air
Cold Air

4. Air moves from areas of HIGH pressure to areas of LOW pressure.
Wind Notes:
Air moves from areas of HIGH pressure to areas of LOW pressure.
This movement of the air is the wind
Example: When you blow up a balloon, you increase the air pressure inside the balloon. When you let go of the end, the air rushes out of the balloon

5. What causes differences in air pressure?
Differences in air pressure are caused by UNEVEN HEATING of the Earth’s surface by the sun. Some air is warmer and some is cooler
Therefore, the sun and solar energy is the ultimate cause of the wind.

6. Measuring Wind Speed and Direction
Wind speed is measured using an anemometer
Wind direction is measured with a wind vane and wind sock

7. Air Pressure on a Weather Map
Areas of High and Low pressure on shown on a weather map with an H or an L.

8. Air Masses
A large body of air that has properties similar to the part of the Earth’s surface over which it develops.

9. Land heats and cools faster than the sea
Land heats and cools faster than the sea. Water retains heat longer than land, and also takes longer to heat and cool.
Think about swimming pools. . .

10. Water has a higher specific heat than land
Water has a higher specific heat than land. Specific heat is the amount of heat (per unit mass) required to raise the temperature of a substance by 1° Think about the way that land and water can affect air masses? What happens to the beach during the day? Is it the same at night? C

11. During the day, the land heats up faster, the hot air rises, creating an area of lower pressure. Wind blows from the sea to the land. This is a sea breeze.

12. At night, the land cools off faster than the sea
At night, the land cools off faster than the sea. Cooler air descends creating an area of higher pressure. Wind blows from the land to the sea. This is a land breeze.

13. Anenometer Lab