By admin_wla |
Tue, 4 Feb 2014 - 12:13
The temperature of the air near the surface of the Earth, usually determined by a thermometer in an instrument shelter about 2 m above the ground. The true daily mean, obtained from a thermograph, is approximated by the mean of 24 hourly readings and may differ by 1.0 degrees C from the average based on minimum and maximum readings. The global average surface air temperature is 15 degrees C. Source: NASA (http://earthobservatory.nasa.gov/Glossary)
