The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Heat Index

in astronomy, the difference between the visual and radiometric magnitudes of a celestial body. Like the color index, the heat index characterizes the energy distribution in the spectrum of the body. The heat index of A0 type stars is taken as zero point. Radiometric observations are performed using detectors that register all the energy incident on them. Such detectors include bolometers, thermocouples, and radiometers. Heat indices are used to determine stellar temperatures. The concept of heat index was introduced in the 1920’s.

References in periodicals archive

Limit outdoor activities during humid days (high heat index).

Heat stress

Livestock become uncomfortable when our heat index reaches about 90[degrees]F, but the biggest concern is humidity.

Heat, humidity & livestock. (The cow barn)

The latest heat index in Guiuan is slightly lower than the 51.7[degrees]C in Dagupan City, Pangasinan on April 9, the highest heat index recorded so far this year.

Cloudy, rainshowers over most parts of PH Saturday

The weather bureau added that a heat index of 41AdegC or higher is considered to be in the 'danger' level and poses health risks.

Highest heat index so far this year at 52.2 C recorded in Catanduanes

Heat index possibly up to 105 Monday, advisory warns

For the same 25 cases, a Heat Index screening threshold of 85 degrees Fahrenheit could identify potentially hazardous levels of workplace environmental heat when WBGT was unavailable.

Occupational Exposure Limits for Heat Stress Often Exceeded: CDC; Heat stress exceeded exposure limits in all 14 fatalities, eight of 11 non-fatal heat-related illnesses

The temperature kept increasing and humidity levels decreasing, causing the heat index to remain lower than the actual temperature.

City of lights sizzles as mercury soars to 46EC

With an average heat index, which records temperature and humidity, hitting 50C, the Arabian Gulf is one of the hottest operating areas of the US Navy.

Heat illness major challenge for 5000 sailors on US aircraft carrier

The researchers utilized historical weather records and also accounted for missing weather data to create the new definition, which considers relative and absolute heat index thresholds for a given area and period of time.

Defining a heat wave

This drop in temperature is less likely felt by the body because the apparent temperature or heat index is high.

High humidity at night to persist

New York City is one of several places where alerts of excessive heat are triggered by rises in the maximum heat index, a combination of heat and humidity conditions that are forecast for the succeeding 24-48 hr.

When to warn? Comparing heat indices to evaluate public health risks