Categories: Guide to Space

What Causes Wind?

It was not until recent memory that what causes wind was understood. Wind is caused by air flowing from high pressure to low pressure. The Earth’s rotation prevents that flow from being direct, but deflects it side to side(right in the Northern Hemisphere and left in the Southern), so wind flows around the high and low pressure areas. This movement around is important for very large and long-lived pressure systems. For small, short-lived systems (outflow of a thunderstorm) the wind will flow directly from high pressure to low pressure.

The closer the high and low pressure areas are together, the stronger the pressure gradient, so the winds are stronger. On weather maps, lines of constant pressure are drawn(isobars). These isobars are usually labeled with their pressure value in millibars (mb). The closer these lines are together, the stronger the wind. The curvature of the isobars is also important to the wind speed. Given the same pressure gradient (isobar spacing), if the isobars are curved anticyclonically (around the high pressure ) the wind will be stronger. If the isobars are curved cyclonically (around the low pressure) the wind will be weaker.

Friction from the ground slows the wind down. During the day convective mixing minimizes this effect, but at night(when convective mixing has stopped) the surface wind can slow considerably, or even stop altogether.

Wind is one way that the atmosphere moves excess heat around. Directly and indirectly, wind forms for the primary purpose of helping to transport excess heat in one of two ways: away from the surface of the Earth or from warm regions(tropics) to cooler regions. This is done by extratropical cyclones, monsoons, trade winds, and hurricanes. Now, you have the answer to what causes wind and its primary function on our planet.

We have written many articles about the wind for Universe Today. Here’s an article about wind energy, and here’s an article about how wind power works.

If you’d like more info on wind, check out Visible Earth Homepage. And here’s a link to NASA’s Earth Observatory.

We’ve also recorded an episode of Astronomy Cast all about planet Earth. Listen here, Episode 51: Earth.

Jerry Coffey

Jerry Coffey is a Registered Nurse and father of 5. He enjoys skydiving, astronomy, and time with his children.

Recent Posts

SpaceX Reveals the Beefed-Up Dragon That Will De-Orbit the ISS

The International Space Station (ISS) has been continuously orbiting Earth for more than 25 years…

1 day ago

Gaia Hit by a Micrometeoroid AND Caught in a Solar Storm

For over ten years, the ESA's Gaia Observatory has monitored the proper motion, luminosity, temperature,…

2 days ago

Lunar Infrastructure Could Be Protected By Autonomously Building A Rock Wall

Lunar exploration equipment at any future lunar base is in danger from debris blasted toward…

2 days ago

Why is Jupiter’s Great Red Spot Shrinking? It’s Starving.

The largest storm in the Solar System is shrinking and planetary scientists think they have…

3 days ago

ESA is Building a Mission to Visit Asteroid Apophis, Joining it for its 2029 Earth Flyby

According to the ESA's Near-Earth Objects Coordination Center (NEOCC), 35,264 known asteroids regularly cross the…

3 days ago

The Most Dangerous Part of a Space Mission is Fire

Astronauts face multiple risks during space flight, such as microgravity and radiation exposure. Microgravity can…

3 days ago