Rule of thumb

[solbjerg]

Hi all

I have been fooling around with Wind Chill formulas like fx.

13,12+0,6215*t-13,96*v^0,16+0,4867*t*v^0,16

Where t is temperature in °C, and v the velocity of the wind in meters per second.

But I really wanted to find a sort of rule of thumb that was much easier to use without having access to a pocket calculator or to a computer with fx. Excel.

One possibility could be v/20*(20-t) it seems to be only a couple of degrees wrong and this is within the uncertainty of the other formula. (False)

I am not going to use that when computing in my head :-)

Example:

13,12+0,6215*10-13,96*10^0,16+0,4867*10*10^0,16 = 6,19°C

p.s. some configurations in the rule of thumb are totally wrong, - back to the drawing board :-(

I removed my initial rule of thumb, will try to come up with a better one :-)

 

It is quite a jungle out there - I found the Fahrenheit and miles per hour (nautical miles mind you)

Wind Chill (F°) = 35,74 + 0,621*t – 35,75*(v^0,16) + 0,4275*t*(v^0,16)

 

With 10°C = 50°F

With 10 m/s = 19,438 mph (nautical)

 

= 35,74 + 0,621*50 – 35,75*(19,438^0,16) + 0,4275*50*(19,438^0,16) = 43,68°F → 6,49°C

(the km/t and °C formula yields 6,19°C)

Not too far from the other formula! But a little less cooling in America :-)

 

Sorry - too complicated to find a good rule of thumb for all instances.

http://forums.iobit.com/attachment.php?attachmentid=6866&stc=1&d=1298640473

Cheers

solbjerg