Why does weather travel from west to east

Skip to main content. You are here Advice » Question of the Day. Share: Question: If global weather generally moves west to east, why does a hurricane move east to west? Let's see if we can offer up a simpler explanation. The Coriolis force is an apparent force due to the rotation of the earth.

Moving objects, such as wind, are deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. Bob Dylan claims you don't need a weatherman to know which way the wind blows: A north wind blows from the north.

By the way, if you stand with your back to the wind and extend your right arm to the right of your body, it points toward high pressure.

Your left arm, extended to the left side of your body, will point toward low pressure. In the Southern Hemisphere, it's the opposite. The weather can be as simple as knowing right from left. The Coriolis force is named for Gaspard Coriolis, a nineteenth-century French scientist who figured out why weather systems spin. For purists, he really didn't discover a force? In any case, we begin with the knowledge that the earth is in motion. It is rotating on its axis.

It goes around once a day. The atmosphere is attached to the earth because of gravity, so it goes around once a day, too, otherwise we would pass through the entire world's weather in just 24 hours.

The following figure shows what's going on. If you've got a globe handy, you might want to refer to it as you read this. Near the equator, where the earth is obviously widest, the outer edge of the earth's atmosphere is moving faster than it does around the poles.

So the atmosphere gains a more west-to-east spin at the equator than, for example, at a latitude of 45 degrees north. Let's say a system is moving north toward your town. It picks up a greater eastward momentum due to the extra force at the equator. So that system may have been heading straight toward you, but it arrives to the east, because of that eastward push.

The eastward momentum, or motion, that system had near the equator is conserved, so the atmosphere is moving faster to the east than the earth is at that latitude. And this is what Coriolis force is all about. However, backdoor cold fronts move in from the northeast. Tropical cyclones develop over the warm waters of either the Gulf of Mexico, the Caribbean Sea, or the Atlantic Ocean.

They are pushed along by winds known as the "easterlies," which moves them generally from east to west across the tropical waters.

So, when a tropical system makes landfall across the U. Open in Our App. Download it here. By Meteorologist Deitra Tate Nationwide. The easterlies, or trade winds, tend to direct tropical systems from east to west Backdoor cold fronts bring in showers opposite the direction of typical cold fronts.