After completing this lesson, you will be able to explain what a local wind is, give some examples of types of local winds, and know where they might be found. A short quiz will follow.
What Is a Local Wind?
Wind is everywhere. It flows through a quiet valley, across every sea, and along coasts and beaches. Wind causes clouds to move over and rain on the city next door or makes your hat blow off and fly down the street. This of course isn't to be confused with the kind of wind that causes people to have to hold their noses in crowded classrooms. No, this kind of wind is a flow of the air across parts of the earth.
Winds can be global or local. Global winds travel large distances and fall into general patterns. Trade winds tend to flow diagonally toward the equator, easterlies go west, and westerlies go east. But in today's lesson, we're talking about local winds.
Local winds are on a much smaller, nearby scale. Your particular home city might have winds that tend to come from the east during one season and the west during another. Or, it might be totally different. The pattern of typical winds you get in a local area is what we call a local wind. Usually they're on the scale of tens of miles to hundreds of miles. These winds can be cold or hot, dry or wet. They can be mild and safe or violent and dangerous. Local winds have a big affect on the weather conditions. They move clouds and moisture around and can make an area wetter or dryer.
Sea and Land Breezes
Let's go through a few examples. One kind of local wind is a sea breeze. A sea breeze happens because the land and sea are heated differently. During the day, the land heats faster than the sea because it takes the sun longer to warm the entire ocean than just a few inches of land. The land then heats the air above it, whereas the air above the ocean stays cooler.
The pressure and temperature of any gas, including air, are directly proportional, according to Gay-Lussac's law. This gas law shows that, if the mass and volume of any given sample of gas are held constant, as the sample's temperature increases, so too will its pressure, and vice versa. This is because greater temperature causes the molecules of gas to have greater kinetic energy, which results in an increased number of collisions with the walls of their container, increasing pressure.