Wind
Wind is the horizontal movement of air from regions of high atmospheric pressure to regions of low atmospheric pressure, caused by differential heating of the Earth's surface. The speed and direction of wind are determined by the pressure gradient force, the Coriolis effect (due to Earth's rotation), and friction with the surface. Wind is a major driver of weather patterns, ocean currents, and climate, and is harnessed as a renewable energy source through wind turbines.
Key Formula
v = -(1 / (ρ × f)) × (ΔP / Δn)
LaTeX: v = -\frac{1}{\rho f} \frac{\Delta P}{\Delta n}
| Symbol | Meaning | Unit |
|---|---|---|
| v | Wind speed (geostrophic approximation) | m/s |
| ρ | Air density | kg/m³ |
| f | Coriolis parameter (2Ω sin φ) | s⁻¹ |
| ΔP/Δn | Pressure gradient across distance n | Pa/m |
Beaufort Wind Scale
| Beaufort Number | Description | Wind Speed (km/h) | Observable Effect |
|---|---|---|---|
| 0 | Calm | < 1 | Smoke rises vertically |
| 2 | Light Breeze | 6–11 | Leaves rustle |
| 4 | Moderate Breeze | 20–28 | Small branches move |
| 6 | Strong Breeze | 39–49 | Large branches in motion |
| 8 | Gale | 62–74 | Twigs break off trees |
| 12 | Hurricane | > 117 | Severe widespread damage |
Interactive Tools
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Related Terms
Atmospheric Pressure
Atmospheric pressure is the force per unit area exerted by the weight of the overlying column of air in the atmosphere on any surface below it. At sea level, the standard atmospheric pressure is 101,325 Pa (or 1013.25 hPa / 1 atm), and it decreases with altitude as the mass of air above decreases. Atmospheric pressure differences drive wind and weather systems: low-pressure zones are associated with storms and clouds, while high-pressure zones bring clear, calm conditions.
Coriolis Effect
The Coriolis Effect is the apparent deflection of moving objects — including air and water — caused by Earth's rotation. In the Northern Hemisphere, objects are deflected to the right of their direction of motion; in the Southern Hemisphere, they are deflected to the left. This effect is responsible for the rotation of large-scale weather systems such as cyclones and anticyclones, as well as global wind patterns like the trade winds and westerlies.
Cyclone
A cyclone is a large-scale atmospheric system with low central pressure, around which winds spiral inward — counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere due to the Coriolis Effect. Tropical cyclones (known as hurricanes in the Atlantic and typhoons in the Pacific) are intense, warm-core systems that derive energy from warm ocean water, while extratropical cyclones are cold-core systems associated with mid-latitude weather fronts. Cyclones bring heavy rainfall, strong winds, and storm surges, and are among the most destructive natural weather phenomena.
From Old English "wind," related to Old Norse "vindr" and Gothic "winds," all derived from Proto-Indo-European "wḗntos" (wind), related to Latin "ventus" and Sanskrit "vāta" — all meaning air in motion.