On food and cooking the science and lore of the kitchen ( PDFDrive ) 1469
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frequently.
Convection:MovementinFluids
Intheformofheattransfercalledconvection,
heatistransferredbythemovementof
moleculesinafluidfromawarmregiontoa
coolerone.Thefluidmaybealiquidsuchas
water,oritmaybetheairorothergases.
Convectionisaprocessthatcombines
conductionandmixing:energeticmolecules
movefromonepointinspacetoanother,and
thencollidewithslowerparticles.Convection
isaninfluentialphenomenon,contributingas
itdoestowinds,storms,oceancurrents,the
heatingofourhomes,andtheboilingofwater
onthestove.Itoccursbecauseairandwater
takeupmorespace—becomelessdense—
whentheirmoleculesabsorbenergyandmove
faster,andsotheyrisewhentheyheatupand
sinkagainastheycooloff.
Radiation:thePureEnergyOfradiantHeatand
Radiation:thePureEnergyOfradiantHeatand
Microwaves
Weallknowthattheearthiswarmedbythe
sun.Howdoessolarenergyreachusacross
millionsofmilesofnearlyemptyspace,
wherethere’snothingtheretoconductor
convect?Theansweristhermalradiation,a
processthatdoesnotrequiredirectphysical
contactbetweenheatsourceandobject.All
matteremitsthermalradiationallthetime,
thoughnormallywecandetectitonlywhen
somethingisveryhot.Thewarmthwefeel
fromsunlightorastoveburnercomesfrom
thermalradiation.It’semittedbyatomsand
moleculeswhich,havingabsorbedenergy,
releaseitagainnotintheformoffaster
movement,butaswavesofpureenergy.
Radiant Heat Is Invisible “Infrared”
Radiation As unlikely as it may seem,
radiated heat is close kin to radio waves,
microwaves,visiblelight,andXrays.Eachof
