Subject: What is the optimum temperature for a hair dryer?

I got to thinking about how we use "hair dryers."

It is assumed that the warm air dries you hair quicker than cold air.
Does this hold true?  Is it just a comfort factor?
I assume that lots of variables go into some equation, temperature, 
velocity, hair thickness, moisture content and more.
Are hair driers designed via science or economics?

Do you think that there might be some general formula that might help 
explain how these devices work?

Re: What is the optimum temperature for a hair dryer?