[meteorite-list] Ram pressure question

[Patrick Wiggins]

Hi all,

Could someone please explain what "ram pressure" is?

Has it got something to do with when air is compressed it heats up so when a meteor passes through the atmosphere it compresses the air in front of it causing the air's temperature to rise and it's that heat that ablates all but the very small meteors?

Many thanks,

patrick
N Utah USA

On 23 Nov 2010, at 15:03, Chris Peterson wrote:

> Heating is due to ram pressure for bodies larger than a few millimeters. For very small particles, ram pressure is not a factor because of the large distance between air molecules compared with the cross-sectional area. These small particles do heat up as the result of collisions with molecules, in a process that is analogous to friction.
> 
> In other words, for all bodies that produce meteorites, frictional heating effects are insignificant.
> 
> Chris
> 
> *****************************************
> Chris L Peterson
> Cloudbait Observatory
> http://www.cloudbait.com
> 
> 
> ----- Original Message ----- From: "JoshuaTreeMuseum" <joshuatreemuseum at embarqmail.com>
> To: <meteorite-list at meteoritecentral.com>
> Sent: Tuesday, November 23, 2010 2:22 PM
> Subject: [meteorite-list] Temperature of meteorites
> 
> 
>> I was under the impression that it's a myth that direct friction from O and N molecules on the surface of a meteorite create the heat that causes ablation.  I thought that ram pressure in front of the meteorite was the main factor in generating heat. The KE and PE would create a hot  shock layer which would flow back around the meteorite causing its outer layer to melt.  I would think that friction is a minor factor,  unless you're talking about ram pressure as a kind of friction.
>> 
>> Phil Whitmer