Windchill factors

[icefest]

This is the fork from this thread:
Subject: Another death on Overland Track

Wind chill is a function of the temperature difference between body temperature and wind speed.

This means that the same wind increase at a lower temperature lowers the apparent temp by more than if it were warmer.

Of course this is simplified, there's a lot more to it. Tell me if you want a more complicated or simplified answer.

To be honest, I prefer the australian apparent temperature index.

Ta is dry bulb temerature,
e is the vapor pressure
ws is wind speed at 10m.

It works better at around 0, and takes into account humidity. (More saturated air feels warmer as you have less evaporative cooling)

[wayno]

http://en.wikipedia.org/wiki/File:WindC ... arison.GIF

[icefest]

They both do not take moisture in account.

Also, for Australian use -15 deg C is phenomaly rare.

[wayno]

charts here and a plain english explanation of windchill. i've used metservice charrts which are 2001, BOM are using charts generated from 1994 and there has been a revision of the charts at some stage

note further down is a chart showing how thick your insulating layer should be for a given windchill

[Gadgetgeek]

I always thought dryer air felt warmer at cool temps, but maybe there is a window where the reverse is true? I liked the old BTU system of windchill used in Canada, I don't know if it was better, but it seems like it gave more info. And since frostbite was always the more immediate concern we always had the good old "exposed flesh will freeze in x seconds" kinda freaky when it got in to the 20s.

[wayno]

charts here and a plain english explanation of windchill. i've used metservice charrts which are 2001, BOM are using charts generated from 1994 and there has been a revision of the charts at some stage

note further down is a chart showing how thick your insulating layer should be for a given windchill

i left out the link, here it is
http://blog.metservice.com/2010/01/feels-like/