HORTICULTURE

Detailed explanation-1: -One degree-day is one day (24 hours) with the temperature above the lower developmental threshold by one degree. For instance, if the lower developmental threshold for an organism is 51°F and the temperature remains 52°F (or 1° above the lower developmental threshold) for 24 hours, one degree-day is accumulated.

Detailed explanation-2: -It is known that degree-hour values are calculated simply by summing up the differences between the hourly dry-bulb temperatures and a standard reference temperature (base temperature). Instead of hourly outdoor temperature, daily average outdoor temperature is used in degree-day calculations.

Detailed explanation-3: -Degree days are the difference between the daily temperature mean, (high temperature plus low temperature divided by two) and 65°F. If the temperature mean is above 65°F, we subtract 65 from the mean and the result is Cooling Degree Days.

Detailed explanation-4: -Cooling Degree Hours The number of CDH generated during an hour equals the outdoor dry bulb temperature minus the balance-point temperature which is 18 deg.