Air temperature usually decreases with increasing altitude. However, during the winter, thanks to a phenomenon called thermal inversion, the temperature of air warmed by the sun in mountains above a fog may rise above the freezing point, while the temperature at lower elevations remains near or below 0ºC. Use the accompanying graph to estimate the rate at which temperature T is changing with respect to altitude h at an altitude of 1,000 meters and also at 2,000 meters.

Air temperature 10 T (C) -10- 2,000 Altitude (meters above sea level) 1,000 3,000 h