AOSC Lesson 3

Temperature Scales Temperature scales are defined by upper and lower calibration points (fixed points) In the Fahrenheit temperature scale the lower fixed point of 0°F is defined as the temperature of a mixture of salt and ice. Dr. Fahrenheit was a physician, and he defined the upper fixed point, 100°F, as the average temperature of his (sick?) patients. In the Centigrade (Celsius) scale, the lower fixed point, 0°C, is defined as the temperature of the melting point of ice, while the upper fixed point, 100°C, is defined as the boiling point of water. The Kelvin scale is a scientific scale. Here the lowest fixed point 0°K is defined as the theoretically lowest temperature that can be reached. On this scale the melting point of ice is about 273°K. One degree K = one degree C.

Fig. 2-1, p. 29

Table 2-1, p. 30 Specific Heat

How is energy transferred in the atmosphere? Tornados, Hurricanes, Severe Storms all require a large energy source. All of this energy comes from the Sun. So, how is this energy transferred within the atmosphere? Five major processes, (1) conduction (2) convection (3) advection (4) transfer of radiation (5) latent heat of vaporization of water

Fig. 2-2, p. 30 CONDUCTION

Fig. 2-3, p. 31 CONVECTION

Fig. 2-4, p. 31 ADVECTION

Transfer of Energy in the Atmosphere CONDUCTION TRANSFER OF ENERGY THROUGH MATTER AIR IS A POOR CONDUCTOR ONLY IMPORTANT AT THE EARTH'S SURFACE CONVECTION TRANSFER OF ENERGY BY MOVEMENT OF MASS CAN ONLY TAKE PLACE IN LIQUIDS – IN SCIENTIFIC TERMS AIR IS A LIQUID. ENERGY ACQUIRED AT SURFACE OF EARTH IS TRANSPORTED UPWARD BY CONVECTIVE FLOW CONVECTION ON A GLOBAL SCALE CREATES WORLDWIDE ATMOSPHERIC CIRCULATION ADVECTION HORIZONTAL MOVEMENT OF AIR

Fig. 2-5, p. 33 PHASE CHANGES OF WATER

Latent heat – Changing the Phase of Water LATENT HEAT IS THE HEAT ABSORBED OR RELEASED BY UNIT MASS OF WATER WHEN IT CHANGES PHASE. –LATENT HEAT OF MELTING / FUSION –LATENT OF VAPORIZATION / CONDENSATION –LATENT HEAT OF SUBLIMATION / DEPOSITION THIS GIVES US ANOTHER WAY OF TRANSFERRING ENERGY IN THE ATMOSPHERE THE OCEANS ABSORB SOLAR ENERGY TO EVAPORATE WATER VAPOR. THE WATER VAPOR IS TRANSPORTED BY WINDS ETC WHEN THE WATER VAPOR CONDENSES TO FORM CLOUDS THE LATENT HEAT IS RELEASED. THE LATENT HEAT RELEASED IS THE SOURCE OF ENERGY THAT DRIVES SEVERE WEATHER, E.G. HURRICANES.

Fig. 2-6, p. 34 Radiation Energy is transferred to the Earth from the sum by electromagnetic waves. Other examples of electromagnetic waves are microwave and radio waves. Each wave is characterized by a wavelength(the distance between successive peaks) and a frequency ( the number of peaks that pass by per second)

Fig. 2-7, p. 34 ELECTROMAGNETIC SPECTRUM

Wien’s Displacement Law: Stephan-Boltzmann Law: Laws of Radiation

Fig All things emit thermal radiation. This is a picture of a person holding a match. It was taken with a camera sensitive to infrared radiation.

Fig. 2-8, p. 36 Note that the peak of the Earth’s radiation occurs at 10  m while that for then sun is at 0.5  m, a ratio of 20. The ratio of the temperatures is 1/20. (Wien’s Displacement Law)

SEVERAL QUESTIONS WHY DOES THE EARTH HAVE SEASONS? WHY ARE THE POLES COLD YET THE EQUATOR IS HOT? WHY IS DAYLIGHT LONGER IN THE SUMMER THAN IN THE WINTER?

Fig. 2-14, p. 43

Fig. 2-11, p. 41

Fig. 2-12, p. 42 HEATING OF THE EARTH’S SURFACE DEPENDS ON THE AMOUNT OF SOLAR RADIATION PER UNIT AREA. SAME AMOUNT OF RADIATION IS DISTRIBUTED OVER A LARGER AREA IN A THAN IN B. RADIATION PER UNIT AREA IS LESS IN A THAN IN B. LESS HEATING IN A THAN IN B.

Fig. 2.15