TuesdayApril 10, 2012 (Atmospheric Heating)
The Launch Pad Tuesday, 4/10/12 List and define the three mechanisms of heat transfer? conduction convection radiation
Announcements • I will be available after school today until 4:45.
Latest News U.S. Records Warmest March; More Than 15,000 Warm Temperature Records Broken Click below for article: http://www.sciencedaily.com/releases/2012/04/120410114021.htm?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+sciencedaily+%28ScienceDaily%3A+Latest+Science+News%29&utm_content=Google+Feedfetcher
Activity • Please take out a blank sheet of paper and put your name, date, and period on it. • Use today’s slides to write five multiple choice questions concerning Atmospheric Heating.
Atmospheric Heating Heat is the flow of thermal energy, and is always transferred from warmer to cooler objects. There are three mechanisms of heat transfer: Conduction through molecular activity. Convection is mass movement within a substance, usually vertical motions. Radiation(electromagnetic radiation) travels at a velocity of 186,000 miles per second in a vacuum.
Mechanisms of Heat Transfer Figure 16.17
Atmospheric Heating radio waves, microwaves, waves, infrared, visible, ultraviolet (UV),x-rays, gamma (very short waves) Radiation(electromagnetic radiation) consists of different wavelengths of energy:
Visible light consists of an array of colors we commonly call the “colors of the rainbow.” Rainbows are relatively common optical phenomena produced by the bending of light by drops of water.
Atmospheric Heating Electromagnetic radiation is governed by basic laws. All objects, at whatever temperature, emit radiation. Hotter objects radiate more total energy per unit area than do cooler objects. The hotter the radiating body, the shorter the wavelength of maximum radiation. Hotter objects emit most of their radiation at shorter wavelengths; hence they will appear to be bluer . Cooler objects emit most of their radiation at longer wavelengths; hence they will appear to be redder. Objects that are good absorbers of radiation are good emitters as well.
Atmospheric Heating The Earth’s atmosphere is largely transparent to incoming solar radiation. Atmospheric effects include: reflection (a surface’s albedo is the percent of solar radiation reflected.) scattering absorption Most visible radiation reaches the Earth’s surface, and about 50% is absorbed at the surface.