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Heat and Heat Transfer Methods

99 Introduction to Heat and Heat Transfer Methods

In figure a, a girl is standing with her hands inside her warm jacket. Behind the girl’s body appears a big wavy upward orange colored arrow. In figure b, the globe of Earth is shown. The Earth’s molten interior is visible through a cross-section in the front of the globe.
Figure 99.1: (a) The cold sensation experienced on a clear, breezy night results from radiative heat loss to the cold atmosphere and space. (b) Earth’s interior remains molten even after billions of years, due to ongoing radioactive decay. This continued heating balances the loss of energy through heat transfer to the surface and into space. (credit: modification of work by NASA Earth Observatory)
A drawing of a person standing while holding a paper on which appear to be data tables. In the background are various instruments including flasks and pumps.
Figure 99.2: Eunice Newton Foote was the first to experimentally demonstrate the heating effect of gases such as carbon dioxide and water vapor. Her pioneering work laid the foundation for our understanding of [pb_glossary id="5962"]greenhouse gases[/pb_glossary] and their role in Earth’s climate system. (credit: Carlyn Iverson, NOAA Climate.gov)

Energy appears in many forms, but one of the most pervasive in biology and health science is heat. Unlike other energy types, heat only exists during energy transfer and is always associated with movement—either of particles, waves, or thermal gradients. Heat transfer plays a critical role in processes ranging from cellular metabolism to weather systems and global climate dynamics.

For example, the chilling effect of nighttime air is not just due to cold temperatures but also to rapid radiative heat loss from the body to the atmosphere. On a much larger scale, Earth’s interior should have cooled long ago were it not for continuous heating from radioactive decay. Both of these phenomena can be explained using the physics of heat transfer.

This chapter explores the mechanisms by which heat is transferred—conduction, convection, and radiation—and their effects on biological and environmental systems. These principles help us understand everything from the design of medical thermal devices to the behavior of the Earth’s climate system.

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College Physics 1 Copyright © 2012 by OSCRiceUniversity is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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