Meteorology uses pressure as the vertical coordinate and not height. This works out better for thermodynamic computations that are done on a regular basis. Pressure decreases in the atmosphere exponentially as height increases reaching 0 pressure in space. The standard unit of pressure is millibars (mb or hectopascals-hPa) of which sea level is around 1015 mb. Standard pressure levels and approximate heights:
Pressure Approximate Height Approximate Temp
Sea level 0 m 0 ft 15 C 59 F
1000 mb 100 m 300 ft 15 C 59 F
850 mb 1500 m 5000 ft 5 C 41 F
700 mb 3000 m 10000 ft -5 C 23 F
500 mb 5000 m 18000 ft -20 C -4 F
300 mb 9000 m 30000 ft -45 C -49 F
200 mb 12000 m 40000 ft -55 C -67 F
100 mb 16000 m 53000 ft -56 C -69 F
