Air Movement on Earth
Outline What is wind? What causes it? What are some common wind patterns? Surface winds Jet stream Sea and land breezes
Earth is a rocky, inner planet with liquid water on over 70% of its surface.
Having two different types of surface (land and water) strongly affects the wind produced on Earth. Which surface heats up more quickly? Sand Which surface cools off more quickly?
Which areas of the Earth receive more direct sunlight and therefore are hotter? Equator gets more direct light and is therefore hotter
Do all areas of Earth have the same amount of sunlight all year long? No! More sunlight hours in summer, therefore it’s hotter.
Surface type (land or water) and temperature (affected by direct/indirect light and hours of sunlight) can cause an uneven heating of Earth’s surface.
As air molecules heat up, they move apart and become less dense This is called low air pressure
Can you answer this? Warm air rises because it is less dense Cold air sinks because it is more dense
What is Wind? Wind is the movement of air from an area of high pressure (cold) to an area of low pressure (warm)
What areas of Earth will have colder (higher pressure) air? Air near the poles will be colder and higher pressure.
The high pressure air from the poles will flow towards the low pressure areas by the equator This causes wind But it doesn’t flow in a straight line as seen in this picture Why?
Wind doesn’t travel in a straight line due to Earth’s rotation on its axis
Wind (and water) in the Northern Hemisphere will turn to the right Wind (and water) in the Southern Hemisphere will turn to the left.
We see this spin in hurricanes N. Hemisphere storms spin counter clockwise S. Hemisphere storms spin clockwise
In which hemisphere is this hurricane occurring? Northern Hemisphere, it’s spinning is counter clockwise
This curving of the wind is called the Coriolis Effect Does it affect the spinning of the water in my toilet? No, the water in the toilet in not a large enough body of water. https://www.youtube.com/watch?v=rdGtcZSFRLk Coriolis Effect on toilets?
All add together to create distinct wind patterns on Earth. Earth’s surface with different surface materials (land or water) Plus, the different amount of solar radiation received (direct or indirect light, and hours of light) Plus, the Coriolis effect All add together to create distinct wind patterns on Earth.
Common Wind patterns Polar Easterlies Westerlies Tradewinds Doldrums http://www.youtube.com/watch?v=qh011eAYjAA Global winds over a year
Trade Winds were important to early explorers and for trade routes
Jet Stream A strong belt of wind in the upper troposphere. It flows from west to east. Pilots take advantage of this when they fly to the East coast.
The jet stream is why we look to the west to find out what type of weather is moving our way.
Local Wind Systems Local areas near bodies of water experience smaller scale wind patterns
Sea breeze During the day, air over the land is heated by conduction. The warmer, less dense air rises The cooler (high pressure) ocean air moves into the low pressure area, resulting in a sea breeze
Land breeze At night, air over the land cools quickly. The cooler, less dense (high pressure) sinks and moves towards the low pressure (warmer) air over the water. Resulting in a land breeze.
Summary Warm air is less dense than cool air Differences in density (temperature) and air pressure cause air movement- wind Coriolis effect causes the wind to turn Wind patterns are observed in different lattitudes A wind pattern seen high in the troposphere is the jet stream Sea breezes and land breezes are patterns of air seen near bodies of water.
Review Videos https://www.youtube.com/watch?v=RzSqhrn2dDM Review of Wind http://earth.nullschool.net/ A visualization of global weather conditions forecast by supercomputers updated every three hours (open in Google Chrome) You can spin the globe and zoom in http://www.youtube.com/watch?v=6hD52H7rQak The Sun as the driving force behind for wind and water currents and earth’s temperatures