Lämpösummaa

Lämpösummaa, often translated as "heat sum" or "growing degree days" (GDD), is a concept used in agriculture, horticulture, and ecology to measure the accumulation of heat over a specific period. It is calculated by summing the daily mean temperatures above a certain base threshold. The base temperature is typically chosen based on the specific crop or organism being studied, representing the minimum temperature at which significant growth or development occurs. For example, a common base temperature for corn is 10 degrees Celsius (50 degrees Fahrenheit).

The calculation involves taking the maximum and minimum temperature for a given day, averaging them to get the daily mean temperature, and then subtracting the base temperature. If the daily mean temperature is below the base temperature, the value for that day is considered zero. This daily heat sum is then accumulated over a period, such as from planting to harvest or from the beginning of the growing season.

Lämpösummaa is a valuable tool for predicting crop development stages, estimating harvest times, and assessing the suitability of a region for growing specific crops. It helps in understanding how the total amount of heat available influences the rate at which plants mature and develop. Different crops have different lämpösummaa requirements for their entire life cycle or for specific phases like flowering or fruiting. By comparing accumulated lämpösummaa with historical data or known requirements, farmers and researchers can make informed decisions about planting dates, irrigation, pest management, and crop selection.