1 Weather and Climate Bay Area Earth Science Institute (BAESI) Energy in the Atmosphere San Jose State University, January 24,

The vertical temperature structure of the atmosphere

3 Weather and Climate There are three modes of energy transmission in the atmosphere.  Conduction: the transfer of energy in a substance by means of molecular excitation without any net external motion.  Convection: the transfer of energy by mass motions within a fluid or gas, resulting in actual transport of energy.  Radiation: the propagation of electromagnetic waves through space. Energy transmission

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Electromagnetic radiation  Radiation is the transfer of energy by rapid oscillations of electromagnetic fields.  The most important general characteristic is its wavelength ( ), ____________________________.  Radiation travels through space at the speed of light (3 x 10 8 m s -1 ). Defined as the crest-to-crest distance

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8 Atmospheric Greenhouse Effect  The atmosphere absorbs some of the Earth’s outgoing longwave radiation.  Which atmospheric gases are most responsible for the greenhouse effect?   In general, the atmosphere acts like a ‘blanket’ absorbing the Earth’s outgoing longwave radiation.

9 Weather and Climate Atmospheric Greenhouse Effect  The atmosphere absorbs some of the Earth’s outgoing longwave radiation.  Which atmospheric gases are most responsible for the greenhouse effect? Water, Carbon Dioxide (CO 2 )   In general, the atmosphere acts like a ‘blanket’ absorbing the Earth’s outgoing longwave radiation.

Figure 1.2: The Earth’s annual and global mean energy balance. Of the incoming solar radiation, 49% (168 Wm -2 ) is absorbed by the surface. That heat is returned to the atmosphere as sensible heat, as evapotranspiration (latent heat) and as thermal infrared radiation. Most of this radiation is absorbed by the atmosphere, which in turn emits radiation both up and down. The radiation lost to space comes from cloud tops and atmospheric regions much colder than the surface. This causes a greenhouse effect.

13 Weather and Climate Sun angle

14 Weather and Climate Sun angle

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18 Weather and Climate What month do you think this graph represents? a) December b) March c) June d) September

19 Weather and Climate What month do you think this graph represents? a) December b) March c) June d) September Answer: December

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