# Atmosphere windspeed limit?

1. Jan 27, 2012

### LKD_

I was reading the Mars article about dunes and I wondered to myself, is there a limit to wind speeds before the wind escapes the planet's gravity and enters into the upper atmosphere, or dissipates in space? Would this be a factor in atmosphere loss that the small planets all seem to have succumbed to?

2. Jan 27, 2012

### Cosmo Novice

See http://en.wikipedia.org/wiki/Escape_velocity for an understanding of escape velocity - as you can infer from the reading wind achieving escape velocity is unlikely.

This http://en.wikipedia.org/wiki/Atmospheric_escape will give you a good basic understanding of the mechanisms behind atmospheric loss.

Hope this helps.

3. Jan 27, 2012

### LKD_

It does. Thank you.

But does the gravity have an effect on maximum windspeed for a planet?

4. Jan 27, 2012

### Cosmo Novice

Theoretically the maximum speed limit would be just under the escape velocity which is derived with M (mass) and r (radius) as a variable. Gravity does not vary (G is the gravitational constant) in the equation, so it is mass and radius which has the variable effect.

Vesc=(2GM/r)2 works for spherical symmetrical bodies with the barycenter being direct center of the spherical object, you can plumb in the values for Mass of the planet, Radii of the planet, use the Gravitational constant and this will give you the escape velocity. Windspeed cannot be higher than this value.

Hope this helps.

EDIT: Need some clarification from more knowledgeable posters but there would need to be EXTREME conditions for this to be likely, but I fail to see any physical restrictions for these speed barring the mechanism for driving windspeed.

5. Jan 27, 2012

### LKD_

Very very helpful. Thanks for being so well versed to answer this.

I'm certain that one could come up with a 1 page equation that would account for a myriad of variables, but the simple understanding fits my level of understanding. Thank you.