Temperature-Humidity Index, or THI, a number used to indicate the discomfort caused by the combined effects of heat and moisture in the air. The formula used to calculate the index is designed to yield a value ranging from 70 to 80. In general, almost all persons are comfortable when the index is 70, and almost no one is when it is 80. In 1985, the National Weather Service officially adopted the Heat Index to replace the THI, but in some areas the THI is still given with summer weather data.
The Freemasons is a secret organization that began in the 1700s and is still in existence today. Who are the Freemasons? And what do they do in their secret meetings?
Every November, the Leonid meteor shower fills the sky with "shooting stars." This year, the shower is expected to peak twice. Learn how Leonid and other meteor showers work.