| Term: | Freezing index |
| Definition: | As used by the U. S. Army Corps of Engineers, the number of Fahrenheit degree-days (above and below 32F) between the highest and lowest points on the cumulative degree-days time curve for one freezing season. For a critical review of the topic see Sakari Tuhkanen (1980). "The freezing index is used as a measure of the combined duration and magnitude of below freezing temperatures occurring during any given freezing season. The index determined for air temperatures at 4.5 feet above the ground is commonly designated as the air freezing index, while that determined for temperatures immediately below a surface is known as the surface freezing-index." (Also called "coldness sun.") |