GEOG1710 1st Edition Lecture 4 Outline of Previous Lecture I The Earth s Wobble II Air and Rain III Albedo and Reflection Outline of Current Lecture I II III IV V Earth s Energy Balance Absorption Thermal Energy Latent Heat and Sensible Heat The Earth s Surface Current Lecture Earth s Energy Balance Sunlight radiation reaches Earth 30 of sunlight is reflected back to space 20 of sunlight is absorbed by the Earth s atmosphere Sunlight is shortwave radiation Earth s surface and atmosphere absorbs 70 of short wave radiation transferred into thermal energy Absorption Process assimilation of radiation by matter and conversion from one form of energy into another Change in wavelength Example photosynthesis solar radiation converted into plant tissue Stratospheric good ozone absorbs UV radiation Converted into thermal energy o Why stratosphere warms up Clouds reflect radiation keeps us cool Clouds absorb radiation keep us warm Aerosols reflect radiation and aerosols absorb radiation depends upon type These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Thermal Energy Balance Convection Conduction and Radiation Conduction when heat diffuses through an object passing from molecule to molecule Energy is being transferred by direct contact of molecules in solids liquids or gases Moves from warm to cold Depends upon material conductivity Conduction imp close to ground Convection when heat is moved from place to place due to warm and cold air masses moving around Heat transfers through mixing of liquids or gases Vertical air motion dominates convection Horizontal motion dominates advection Radiation heat moving through space Energy transferred by electromagnetic waves Doesn t require matter waves can move through space Latent Heat heat stored released when water changes phase Heat energy is moved between surface and atmosphere via evaporation liquid to gas energy stored cooling effect Condensation gas to liquid energy released warming effect ex Sweat and storms Sensible Heat heat you can feel Energy required to change temperatures of a substance no phase change Sensible heat transferred between surface and air when temperature between them differs ex Car window and thermometer Ground warming up the cool air above it The air warming up the cool ground What s on the surface matters Wet locations have higher evaporations than dry locations Trees evaporate more water than grasses Urban heat island higher max and min temperatures than surrounding non urban areas o Why Albedo is low in cities rough texture sealed surfaces cars and industries o Reducing Dallas urban heat island Expand and protect urban tree cover Increase roof reflectivity lower albedo Increase paving reflectivity lower albedo Better public transportation
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