Wind

How Wind Works

Welcome to the "How Wind Works" learning page! Here, we'll explore the fundamentals of wind, focusing on surface wind dynamics, the horizontal pressure gradient, the Coriolis effect in the Northern Hemisphere, and geostrophic wind. By the end of this module, you'll have a solid understanding of how wind is generated and influenced by various forces. Interactive elements and images will help clarify these concepts.

What is Wind?

Wind is the movement of air from areas of high pressure to areas of low pressure. This movement is driven by the uneven heating of the Earth's surface by the sun, which creates pressure differences.

Question: Why does air move from high-pressure areas to low-pressure areas?

Horizontal Pressure Gradient

The horizontal pressure gradient force is the primary force driving wind at the Earth's surface. It arises due to differences in atmospheric pressure across horizontal distances.

High-Pressure Areas: Areas where the atmospheric pressure is higher.
Low-Pressure Areas: Areas where the atmospheric pressure is lower.

The air moves from high-pressure areas to low-pressure areas, creating wind.

Example Image: Horizontal Pressure Gradient

Notice: How the Horizontal Pressure Gradient Force is perpendicular (creating a 90-degree angle) to the line contours

Question: How does a greater pressure difference influence wind speed?

The Coriolis Effect in the Northern Hemisphere

The Coriolis effect is a result of the Earth's rotation. It causes moving air to be deflected to the right in the Northern Hemisphere, affecting the direction of wind.

Rightward Deflection: In the Northern Hemisphere, the Coriolis effect causes wind to curve to the right relative to its direction of motion.
The opposite can be said for the Southern Hemisphere

Example Image: Coriolis Effect

Question: In which direction does the Coriolis effect deflect wind in the Northern Hemisphere? Why?

Geostrophic Wind

Geostrophic wind results from a balance between the horizontal pressure gradient force and the Coriolis effect. It occurs at higher altitudes where friction with the Earth's surface is negligible.

Forces Balance: The geostrophic wind blows parallel to the isobars (lines of constant pressure) when the pressure gradient force and the Coriolis force are in balance.

Example Image: Geostrophic Wind

Question: Why does geostrophic wind blow parallel to the isobars rather than across them?

Quiz

How wind works: Wind Quiz

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