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How would the air move over the earth's surface if the earth did not spin on its axis?
Question Date: 2015-02-03
Answer 1:

The spin of the Earth is not the primary phenomenon driving motions in the turbulent atmosphere. In fact, air moves mostly because the Earth is heated unevenly by the sun.

The rate of solar energy input is a strong function of latitude. Because there is more heating at low latitudes, the air there gets heated and rises. If the earth WAS NOT spinning, this heated air would rise to the top of the troposphere and then it would travel north on a line of longitude and cool off. At the poles it would become denser than the surrounding air and it would sink down towards the surface moving south... as it moved south it would be heated and find itself again at the equator and hot, and hence would rise!! This is a GIANT CONVECTION CELL called the HADLEY CIRCULATION.it is inequities in temperature that gives rise to buoyant air and THAT is what drives atmospheric circulation. The spin of earth does MODIFY the pattern of air motion, but still the main driving effect is the redistribution of planetary heat from low to high latitudes.

Answer 2:

There are three forces that make air move over the earth's surface. The Earth's rotation is only one of them! The Earth's rotation results in an effect called the "Coriolis Effect" described in 1835 by the French scientist Gaspard-Gustave Coriolis. But even if the earth stops rotating, the other two forces will result in winds.

The first force is the due to the difference of air pressure at nearby locations. If an area with high air pressure is next to an area with low air pressure, air will move from the high to the low pressure. The goal is to make the two pressures equal. When the pressure difference is big, there will be lots of air that will have to move to equalize the pressures. It will also move fast: the bigger the pressure difference, the stronger and faster the wind will be. Which is why big difference in pressure predict windy days. You don't have to look very far to see pressure differences. (check it out on the weather channels maps!)

The sea breeze is an example you can observe: during the night, the earth cools down and the sea and earth temperatures are similar. But after noon, around 2pm, when the sun is high up, the earth heats up more than the sea, and the air above the earth heats also more than the air above the sea. Earth air expands and becomes lighter, so moves up. That creates a pressure difference: the coast's earth side has lower pressure then the sea side and air located above the sea, which has high pressure, wants to move towards the earth, which has low pressure, to replace the air that is moving up. The high and low pressure on the map tell us the direction of the wind, and you can see them on all weather channels!

The second reason air moves the way it moves is friction. Forests, buildings, cities, slow down the wind because of their uneven surface. Wind above open sea, flatlands and fields faces no obstacles and can speed up. Friction also makes the wind rotate direction as it slows down. If friction is too much, then the wind can stop.

Knowing these three phenomena, you can predict the local weather very well from the daily pressure maps!

Answer 3:

Interesting question! Air (in the form of wind) is affected by the Earth’s rotation. But it is also affected by areas of high and low pressure.

For instance, the air on top of a mountain is lower pressure and might be displaced by air of higher pressure at sea level. Also, the Sun heats up the atmosphere which causes air to flow as it becomes hotter. The rotation of Earth adds yet another parameter where you can think of it as the Earth “dragging” the air around as it spins. An interesting mathematical theorem you may find interesting is called the “Hairy Ball” Theorem. This is a mathematical proof which in essence says that “you can’t comb a hairy ball flat without a cowlick.” For application of wind direction and the Earth, this suggests that if there is wind on Earth (and there is), at some point on Earth there will always be a point with no wind! Think of this as the eye of a cyclone. So this theorem implies that there will always be a cyclone at some point on Earth.

hairy ball theorem

Answer 4:

Heating of air causes differences in temperature, which causes the air to circulate. Heating of the air can be accomplished in many ways, such as when the sun heats the Earth, which then heats the air up.

For example, think of hot pavement sitting in the sun at midday, which makes the air hot above it. You can sometimes see shimmery patterns above the pavement because the air of different temperature is mixing with the colder air around it.

Another example, of course, is the Earth is covered mostly by water, and water can also be heated by the sun. The water is then carried into the air with this heat, and causes circulation.

Answer 5:

The east-west winds on Earth are largely caused by the Earth's rotation, but the north-south winds generally aren't. If the Earth were not spinning, you could see north-south winds, just not east-west winds.

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