How do clouds keep up with (or travel faster than) the earth's surface?

Question

If the earth at its equator is moving at about 1,000 miles per hour,
(25,000 miles/24 hours) and progressively slower away from the equator, how is it that clouds can keep up and move right along with (or even surpass) the speed the surface below is moving. (For example, cold fronts in North America generally move from the northwest to the southeast, and clouds can make it in just a few days. Why do they even move s.e. at all? Wouldn't the surface just "run off" and leave them, so that clouds always would move west?

Answer 1

Very good question. The answerer who gave the ball on the train analogy has explained the case if our atmosphere were traveling at the same velocity as the velocity of the Earth's rotation (about 1,000 nmph = nautical miles per hour = knots).

But, and this is a BIG BUT, unlike a passenger on a train, the atmosphere is a gas and it does in fact slip a bit as the Earth spins underneath it.

You can see the effect by spinning a ball in a bucket of water. At first, the surrounding water near the ball is motionless (for a very brief moment), but then due to friction forces between the water and the ball, the water starts to speed up and spin around with the ball, but at a slower angular velocity than the ball due to slippage. Similar effect between the atmosphere and the Earth.

If it were not for other forces at work, we on Earth would in fact see high velocity winds due to the Earth's rotation. Gravity, which is not present in the ball in water experiment, tends to pull the atmosphere towards the ground; so the friction forces between the atm and Earth pulls the atm along much better than the ball in water. And last, but definitely not least, our atm is not a uniformly dense gas, which is why there are "high pressure areas" and "low pressure areas."

Like the top of a waterfall, a high pressure area pushes air outward from the center of that high pressure area. Like the bottom of a waterfall, a low pressure area sucks up that air pushed by the high pressure area. Like the water cascading from the top to the bottom of the waterfall, the pushed and sucked air create winds.

And the sum of all these winds tend to flow in a west to east direction. This west to east flow comes from yet another force, the Coriolis effect. This effect, due to differences in Earth's tangential velocity between the equater (where it's greatest) and the poles (where there is none), tends to move air from west to east in the northern hemisphere. Check this out:

"The Coriolis effect strongly affects the large-scale atmospheric circulation, leading to the Hadley, Ferrel, and Polar cells. In the oceans, Coriolis is responsible for the propagation of Kelvin waves and the establishment of the Sverdrup balance." [See source.]

The slip streams are examples of "large-scale atmospheric circulation."

The west to east slip streams at altitudes, where the frictional forces on the air are less than on those near the ground, are examples of the generally west to east direction of winds. These pressure differentials between high and low pressure areas far outweigh any slippage between Earth and its atm.

Answer 2

Surface *area* of Uranus: 8.115E9 km^2. Surface of Uranus: ices (water, ammonia, methane). Not a very hospitable place. It's an ice giant, and can be really thought of having three layers: rocky core, icy mantle, and a gaseous envelope. The core is tiny, perhaps 20% of its mass. The "icy mantle" is not "real" ice: it's a very dense and hot fluid. There are other models of Uranus that fit observations, and we can't really be sure at the moment how Uranus really looks up close and personal, much less if one can talk of a "surface" on it. Just like Jupiter, it doesn't really have a surface. The term "surface" only makes sense when you need one to stop you from falling. On Earth, the atmosphere is so thin that we can't float in it, and instead fall to a more "solid" ground. On Uranus and Jupiter, you won't reach anything "solid" before you stop falling when atmosphere's density equals that of liquid water (your own).

Answer 3

Because the Earth is surrounded by a vacuum, there is no resistance. That means there is nothing stopping the air moving around at the same speed as the planet. Winds are just variations in this constant following of the Earth surface and are due to pressure differences because of temperature differences.

Answer 4

How do clouds move?
Clouds move with the wind. High cirrus clouds are pushed along by the jet stream, sometimes traveling at more than 100 miles-per-hour. When clouds are part of a thunderstorm they usually travel at 30 to 40 mph.

Answer 5

Think about like this:

Imagine you are on a train that is moving at 60 mph. You throw a ball from one end of a car to another. You throw the ball with enough force to make it travel 20 mph. But, the train is already moving at 60 mph, so why doesn't the ball immediately move backwards...after all it is moving 40 mph slower than the train.

Because the 20 mph is relative to the speed of the train. Just like anything moving on Earth is relative to the speed of the planet.

Answer 6

the atmosphere moves with Earth, you know! The surface of the Earth drags the air along (and if for some reason it didn't then you'd have permanent 1'000mph winds at the equator, which as far as I'm aware no one has ever mentioned ;-)

Answer 7

Everything comprised with the ozone layer goes at the same speed.If your logic held,Then maybe we would have 1000mph winds all the time...........

Answer 8

I am not good in this.. but could be wind factor?