The standard question on a knowledge test:
"Under which condition will pressure altitude be equal to true altitude?"
The answer is: "when atmospheric conditions exist, i.e., 29.92" Hg and 15 degrees C at sea level."
What I'm not understanding fully is what the temperature at sea level has to do with pressure altitude. For example, say the sea level pressure is 29.92" Hg but the temperature at sea level is 20 degrees.
Wouldn't pressure altitude still equal true altitude?