A scale of temperature introduced in about 1709 by the German physicist, Fahrenheit, who was the first to use mercury as the thermometric substance. Primary fixed points were the temperatures of a mixture of common salt and ice and the temperature of the human body; with reference to these the freezing point of water was marked 32 degrees, and the boiling point of water was marked 212 degrees.
Fog:
Water droplets in the air that reduce visibility to less than 1,000 m (1,100 yards).
Föhn:
The European name for a dry, downslope wind. Also called "chinook" in North America.
Front:
The boundary between two air masses.
Frost:
White ice crystals deposited on the surface of objects that have a temperature below the freezing point of water.
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Fahrenheit: