Learn about changes in wind direction with this easy experiment!
Steps:
- Are there any flags around you? If not, is there anything else flapping in the breeze? If so, notice the direction that the flag or other flapper is flying. If you draw a line from the flapping end of the flag to the flagpole, your line will point in the direction that the wind is blowing from.
- Wet you finger and hold it up in the air. The wind will feel cool against your wet finger. The side of your finger that is facing the wind will feel coolest.
- Check the direction of the wind in the morning and in the evening. Is it the same?
What’s Going On? During the day, cool breezes often blow from the ocean to the land. In the evening, the breeze often blows from the land back to water.
Why? During the day, the sunshine warms the land. The land then warms the air just above it. Warm air rises and cold air from above the water moves to take the place of the warm air, making a cool sea breeze.
At night, the ocean stays warm while the land cools off. (You may have noticed this if you’ve ever gone for a swim at night; the water feels warmer than the air.) The water warms up the air above it. That warm air rises, and cooler air from the land rushes to take its place, making a breeze from the land to the sea.
Whenever there are two surfaces that absorb heat differently – like ocean and sand or mountain and prairie – that difference creates wind.
Source: Exploratopia, 2006: The Exploratorium.
