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WinterSummerDuring the winter, the lake is warmer than thesurrounding land.During the summer, the lake is cooler than thesurrounding land.Figure 16 Water can absorb andlose a great deal of heat withoutchanging temperature much.The Caloric Theory Atone time heat wasthought to be a fluid,called caloric. A warmobject contained morecaloric than a cold object.Benjamin Thompson inthe late eighteenth centurynoticed that tremendousamounts of heatwere generated duringthe boring of the holes incannons. He concludedthe amount of heatdepended only on thework done by the drill.James Joule later showedthat other forms ofenergy could be convertedinto heat.Research how the workof Thompson and Jouledisproved the caloric theoryof heat.Lakes and Air Temperature How does the temperature ofwater in a lake compare to the temperature of the surroundingair on a hot summer day? How do these temperatures compareat night when the air has cooled off? You might have noticedthat the water is cooler than the air during the day and warmerthan the air at night. This is because it takes longer for a largebody of water to warm up or cool down than it does for the surroundingair and land to change temperature. Even from seasonto season, a large body of water can change temperature lessthan the surrounding land, as shown in Figure 16.Heat on the MoveA transfer of energy occurs if there is a temperature differencebetween two areas in contact. Heat is transferred from warm placesto cooler ones. This transfer can take place in three ways—radiation,conduction, and convection. Conduction transfers heat mainlythrough solids and liquids. Convection transfers heat through liquidsand gases. Radiation can transfer energy through space.Conduction Have you ever picked up a metal spoon that wasin a pot of boiling water and dropped it because the spoon hadbecome hot? The spoon handle became hot because of conduction.Conduction (kun DUK shun) is the transfer of energy bycollisions between the atoms and molecules in a material.As the part of the spoon in the boiling water became warmer,its atoms and molecules moved faster. These particles then collidedwith slower-moving particles in the spoon. In these collisions,kinetic energy was transferred from the faster-moving tothe slower-moving particles farther up the spoon’s handle.174 CHAPTER 6 Energy