Parameter Tree:
EARTH SCIENCE > ATMOSPHERE > ATMOSPHERIC TEMPERATURE > ATMOSPHERIC TEMPERATURE INDICES > COOLING DEGREE DAYS

Definition:
A form of degree-day used to estimate the energy requirements for air conditioning or refrigeration; one cooling degree-day is given for each Fahrenheit degree that the daily mean temperature departs above the base of 24C (75F).

Reference:
Glossary of Meteorology, American Meteorological Society, 2013, http://glossary.ametsoc.org/wiki/Cooling_degree-day