As dry air moves up it cools at 1 degree celsius every 100 meters up to 12 kilometers. So A if the ground is 25 degrees celsius what is the temperature at x kilometers?
T = -10x + 25
Where T = temperature in oC and x = the height above the ground in km. The slope m = -10 because the temperature drops 10oC every km. The y-intercept is 25, so when x=0, T = 25oC.