Pressure and Wind Patterns of the Atmosphere

1. Pressure and Wind Patterns of the Atmosphere Done By: Abdulrahman Al Huwaidi, Saif Al Khawaled, Osama Darweesh, Hamad Abdulwahab

2. Air pressure • Air pressure is the force of air molecules pushing on an area. • The greater the force, the higher the air pressure. • Because air molecules move in all directions, air pressure pushes in all directions.

3. Air is related to altitude and density • Air pressure and density are related. Just as air pressure decreases with altitude, so does the density of air. • Air pressure decreases as you move higher in the atmosphere. • Above each location on Earth is a column of air that stretches to the top of the atmosphere.

4. Air is related to altitude and density • Air pressure and density are higher at sea level because a taller column of air pushes down. • Air pressure and density are lower at a high altitude because a shorter column of air pushes down.

5. Pressure and air motion. • Air pressure differences in the atmosphere affect air in a similar way. • If the air pressure were the same at all locations, air wouldn’t move much. • Because of differences in pressure, air starts to move from areas of higher pressure towards areas of lower pressure.

6. How a barometer works • Air pressure can be measured in different ways. A barometer is any instrument that measures air pressure.

7. Uneven heating causes air to move • Weather is the condition of Earth’s atmosphere at a particular time and space. Wind is an important part of weather. • Wind is air that moves horizontally, or parallel to the ground. • Over a short distance, wind moves directly from higher pressure towards lower pressure.

8. How wind forms • Wind moves from an area of high pressure towards an area of low pressure.

9. How wind forms • Sunlight strongly heats an area of ground. The ground heats the air. The warm air rises, and an area of low pressure forms. • Sunlight heats an area of ground less strongly. The cooler, dense air sinks slowly, and an area of high pressure forms. • Air moves as wind across the surface, from higher towards lower pressure.

10. Global Winds • The distance winds travel varies. Some winds die out quickly after blowing a few meters. • In contrast, global winds travel thousands of kilometers in a steady pattern. • Global winds last for weeks.

11. What causes global winds • Uneven heating between the equator and north and south poles causes global winds.

12. What causes global winds • Sunlight is concentrated near the equator because it strikes the surface directly. • Sunlight is more spread out near the poles because it strikes at a lower angle.

13. Earth’s rotation affects wind direction • If Earth did not rotate, global winds would flow directly from the poles to the equator. • The influence of Earth’s rotation is Coriolis Effect. • Global winds turn as Earth turns beneath them.

14. Calm regions • The air usually stays calm in high-pressure and low-pressure zones. Winds are light and they often change direction. • The doldrums are a low-pressure zone near the equator. • The horse latitudes are high-pressure zones located about 30 degrees north and 30 degrees south of the equator.

15. Wind belts • The trade winds blow from the east, moving from the horse latitudes towards the equator. • The westerliners blow from the west, moving from the horse latitudes toward the poles. • The easterliners blow from the east, moving from the polar regions oward the mid-latitudes.

16. Jet streams flow near the top of the troposphere • Jet streams usually flow in the upper troposphere from the west to the east for thousands of kilometers.

17. Monsoons • Winds that change directions with the seasons are called monsoons.