Why the trade winds blows from east to west while the earth rotation and the jet stream are west to east?


I tried to Google around and didn’t find an answer.

It’s seems there are conflicts with the explanations about earth winds.
One says winds go west to east because of earth rotation and others says its east to west because of Coriolis effect.

Can someone explain it to me simply please?

In: 71

Both are right. The Earth’s rotation causes the Coriolis effects, which is why this happens.

When you look at the earth, and the sunlight that hits it, where does sunlight hit most? The equator. This, the equator is hotter. So now factor into this that hot fluids rise and expand, while cold fluids sink and contract. This is where pretty much all currents and wind and such come from, this convection mechanism. So the hot air at the equator roses, then something has to come in and take its place, that’s cooler air from the north and south. So you can draw lines indicating this. But now that the colder air is leaving the higher latitudes, and the hot air high up is cooling, there is another pressure difference. The (formerly) hot air sinks to replace the cold air that replaced it. And now the cycle is complete. You should have in your mind a vision of a loop. At the equator, air gets hot, goes up, goes north or south, cools down, drops, then goes south or north (opposite of the first one).

Now let’s introduce the spin of the earth, noting that the earth “spins” faster at the equator than near the poles. This is because the land at the equator is further from the axis of rotation than the poles are. Remember, no matter where you are on the earth, it will complete one full rotation in 24 hours! This means the land at the equator must be traveling faster to make it all the way around in that time!

Go back to those cells. The stuff near the equator is moving fast. The stuff away is not. So as that stuff that’s low and cold moves towards the equator, the equator is moving faster underneath it. This looks like, to people on the surface, like westward blowing winds. Voila, trade winds!

Oh but what about that fast moving warm air? Well it’s now over a higher latitude and thus is going faster than the ground in the eastern direction. Oh hey it’s a jet stream!

There are other ways to look at as well and I’m sure others will chime in.

The Coriolis force deflect everything that moves on earth (wind, airplane, water, ect). In the northern hemisphere, this is to the right of the direction of movement (and to the Left in the southern hemisphere). The reason why is a whole different set of explanation, just accept it as truth for now.

In the northern hemisphere, if the wind is blowing directly toward the poles, it will be deflected to the right (east), so the actually wind movement is south-west to north-east. If the wind is blowing from the pole to the equator (you have to face the same direction as the wind, aka standing at the pole and looking at the equator), right of that is west, so the actual wind is north-east to south-west.

So both answer is correct, the Coriolis force can defect the wind in either direction. In the North we have both westerlies and easterlies as a result of the Coriolis force. The trade wind blows toward the equator in the north (North to South) whereas the jetstream is driven by pressure gradient that push air toward the pole (South to North). The Coriolis force push both of them to the right of the direction they are moving in, resulting is both East to West and West to East wind)

The movement of air masses, such as the trade winds and the jet stream, is influenced by various factors that create intricate wind patterns. These patterns might seem contradictory, but they arise due to Earth’s rotation, temperature differences, and atmospheric pressure dynamics.

The trade winds blow from the east to the west in both the Northern and Southern Hemispheres. This phenomenon is primarily driven by Earth’s rotation and the temperature disparity between the equator and the poles. The equator receives more direct sunlight, causing warm air to rise near it and flow toward the poles at higher altitudes. Cooler air from higher latitudes then moves in to replace the rising warm air, giving rise to the east-to-west flow of the trade winds at the surface.

On the other hand, the jet stream is a swift and narrow current of air found at high altitudes. It flows from west to east and is influenced by temperature contrasts between different air masses. Earth’s rotation, known as the Coriolis effect, also influences its trajectory. The jet stream typically forms along the boundary between distinct air masses. The polar jet stream is usually situated at higher latitudes, while the subtropical jet stream is found farther south.

Both the trade winds and the jet stream are shaped by Earth’s rotation, temperature variations, and atmospheric pressure dynamics. The trade winds, which flow from east to west, result from temperature differences between the equator and the poles. Meanwhile, the west-to-east movement of the jet stream at high altitudes is driven by a combination of temperature contrasts and the Coriolis effect.