Temperature–humidity index (THI), combination of temperature and humidity that is a measure of the degree of discomfort experienced by an individual in warm weather; it was originally called the discomfort index. The index is essentially an effective temperature based on air temperature and.
Relative Humidity Heat Index = * Please note: The Heat Index calculation may produce meaningless results for temperatures and dew points outside of the range depicted on the Heat Index Chart linked below.
The relative humidity threshold, below which a heat index calculation will return a number equal to or lower than the air temperature (a lower heat index is generally considered invalid), varies with temperature and is not linear. The threshold is commonly set at an arbitrary 40%.
Temperature Humidity Index: what you need to know about it 01/08/2018. Temperature Humidity Index (THI) is a measure that has been used since the early 1990s. It accounts for the combined effects of environmental temperature and relative humidity and is a useful and easy way to assess the risk of heat stress.
In order to determine the heat index using the chart above, you need to know the air temperature and the relative humidity. For example, if the air temperature is 100°F and the relative humidity is 55%, the heat index will be 124°F. When the relative humidity is low, the apparent temperature can actually be lower than the air temperature.
The Temperature-Humidity Index (THI) is a valuable measure that you know when cows are becoming heat-stressed and to what degree so you can use cooling methods appropriately. Heat stress is caused by a combination of temperature, relative humidity, solar radiation, air movement and precipitation.
This free heat index calculator estimates heat index temperature felt by human body based on the actual measured air temperature together with humidity level or dew point. Also, explore the wind chill and dew point calculators, as well as hundreds of other calculators.
A graph showing the effects of rising temperature and relative humidity on cattle and indicates safe and dangerous zones
The Heat Index is a measure of how hot it really feels when relative humidity is factored in with the actual air temperature. To find the Heat Index temperature, look at the Heat Index Chart above or check our Heat Index Calculator.As an example, if the air temperature is 96°F and the relative humidity is 65%, the heat index--how hot it feels--is 121°F.
The “heat index” is designed as a measure of the “feeling” of a certain combination of temperature and humidity to the human body. This sets it apart from the more objective measure of temperature, but most people will be familiar with the impact of a very humid environment on your perception of heat.