I should have been clearer!
If you specify a temperature, then you have completely specified the TAS which matches Mach 1.
Basically temperature measures the randomly directed kinetic energy of the air molecules, which is a function of their average speed, which determines how fast they can transmit information such as sound waves.
If there is a wind, the Ground Speed of sound is higher in the wind direction, so TAS really is the right measure.
But of course EAS,CAS,IAS etc do differ from TAS depending on density (and various errors).
Last edited by 24Carrot; 16th February 2013 at 17:21.