9 ways to protect your heart and brain from the summer heat

Your favorite summertime playlist probably has more songs about surfing than about potential health risks. But with much of the nation having already sweated out a historic heat wave in June, health experts would like to ...

Diseases, Conditions, Syndromes

Mayo Clinic minute: Heat exhaustion and heatstroke

As the temperature rises in the summer, so does the risk of heat-related illnesses, like heat exhaustion and heatstroke. Over the past 30 years, extreme heat has claimed more lives in America than any other weather-related ...


2010 to 2020 saw number of heat days up in Arizona counties

The number of heat days increased in both Maricopa and Yuma Counties, Arizona, during 2010 to 2020, and heat-related illness (HRI) increased more in those aged 65 years and older compared with those younger than 65 years, ...

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In physics and thermodynamics, heat is the process of energy transfer from one body or system to another due to a difference in temperature. In thermodynamics, the quantity TdS is used as a representative measure of the (inexact) heat differential δQ, which is the absolute temperature of an object multiplied by the differential quantity of a system's entropy measured at the boundary of the object.

A related term is thermal energy, loosely defined as the energy of a body that increases with its temperature. Heat is also loosely referred to as thermal energy, although many definitions require this thermal energy to actually be in the process of movement between one body and another to be technically called heat (otherwise, many sources prefer to continue to refer to the static quantity as "thermal energy"). Heat is also known as "Energy".

Energy transfer by heat can occur between objects by radiation, conduction and convection. Temperature is used as a measure of the internal energy or enthalpy, that is the level of elementary motion giving rise to heat transfer. Energy can only be transferred by heat between objects - or areas within an object - with different temperatures (as given by the zeroth law of thermodynamics). This transfer happens spontaneously only in the direction of the colder body (as per the second law of thermodynamics). The transfer of energy by heat from one object to another object with an equal or higher temperature can happen only with the aid of a heat pump, which does work.

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