Thermal Response of Climate System Current Weather and News Heat Transfer Processes Latent Heat Transfer Heating Imbalances For Next Class: Read rest of Chapter 4 Reminder: Lab will meet next week

Heat Transfer Processes What are the four major heat transfer processes?

Heat Transfer Processes Radiation Both a form of energy and a means of energy transfer Radiational heating: object absorbs radiation at a greater rate than it emits radiation Internal energy increases, temperature rises Radiational cooling: object emits radiation at a greater rate than it absorbs radiation Internal energy decreases, temperature drops © AMS

Conduction Conduction: the transfer of kinetic energy of atoms or molecules via collisions between neighboring atoms or molecules Heat Conductivity: the ratio of the rate of heat transport across an area to the temperature gradient Substances with a higher heat conductivity have greater rates of heat transport Solids are better conductors than liquids, liquids are better conductors than gases © AMS

Convection Convection: the vertical transport of heat within a fluid via motions of the fluid itself Generally only occurs in liquids or gases (fluids) Convection in the atmosphere consequence of differences in air density Advection is the horizontal transport of heat Sensible Heating is the combination of conduction and convection © AMS

Latent Heat Transfer Phase Changes of Water Water occurs naturally in all three phases (solid, liquid, gas) Depending on phase changes, either absorbs or releases heat to or from environment Latent heat: quantity of heat involved in phase changes of water Latent heating: the transport of heat from one location to another as a consequence of changes in the phase of water © AMS

Heat Imbalance: Atmosphere vs. Earth’s Surface Latent Heating Latent heat of fusion: amount of heat required to convert a solid at its melting point to a liquid without a change in temperature Latent heat of vaporization: amount of heat required to convert a liquid to a gas without a change in temperature © AMS

Latent Heat Transfer Phase Changes of Water Heat absorbed from environment during changes to higher energy states melting, evaporation, sublimation Heat released to environment during changes to lower energy states freezing, condensation, deposition © AMS

680 cal/g required 80 cal/g required 540-600 cal/g required 80 cal/g released 540-600 cal/g released 680 cal/g released

Land–Water Heating Differences Figure 5.7

Thermal Response and Specific Heat Specific Heat: amount of heat that will raise the temperature of 1 gram of a substance by 1 Celsius degree Measured relative to liquid water Water has the greatest specific heat of any naturally occurring substance Variation in specific heat from one substance to another implies that different materials have different capacities for storing internal energy © AMS

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Thermal Response and Specific Heat Maritime and Continental Climates Maritime climates: immediately downwind of the ocean, and experience much less contrast between average winter and summer temperature Continental Climates: well inland, experience a much greater contrast between winter and summer temperature © AMS

Heat Imbalance: Atmosphere vs. Earth’s Surface Sensible Heating The Bowen Ratio compares how heat at the Earth’s surface is divided between sensible heating and latent heating Varies from one place to another Depends on amount of surface moisture Surface energy budget through the course of a year © AMS

Bowen Ratio Bowen ratio = (sensible heating)/(latent heating) High Bowen ratio implies more sensible heating than latent heating (i.e., deserts) Low Bowen ratio implies more latent heating than sensible heating (i.e., oceans or water bodies)

Heat Imbalance: Atmosphere vs. Earth’s Surface © AMS