An interesting note about weather balloons (radio-sondes) is that they register altitude by a difference of pressure; pretty much like the altimeter of an aircraft. Maps are then drawn with isotherms (equal temperature) at a standard air pressure. read more
A century ago, scientists could only predict the weather from measurements taken on the ground. With such a limited data set, the best meteorologists can do is predict the weather a few hours into the future. With weather balloons, though, scientists can plot out weather conditions for days in advance. read more