Vertical Structure of Earth's Temperature

R. J. Sica
Department of Physics and Astronomy
The University of Western Ontario
Copyright 1999, R. J. Sica

The horizontal variations in surface temperature have a maximum difference of about 80 °C between the warmest and coldest temperatures. As a function of altitude temperature varies by more than 800 °C between the ground and the top of the atmosphere. Figure 1 introduces us to the atmospheric "spheres." This figure shows how temperature varies with height.

Each region of the atmosphere, as well as the solid Earth and the magnetosphere, is part of geospace, the area of space perturbed by Earth's environment. The atmospheric regions can be thought of as spherical shells or spheres which surround Earth. The top of each sphere is called a "pause". For instance, the lowest part of the atmosphere, from the surface to about 12 km, is called the troposphere. The top of the troposphere, where the temperature reaches a local minimum, is called the tropopause. The troposphere, where we spend most of our lives, seems awfully small on this scale, so let's magnify the troposphere and the middle atmosphere (the stratosphere and mesosphere; Fig 2).

The variation of temperature with height in Earth's atmosphere. The horizontal dotted lines delineate the atmospheric "spheres." Above 300 km the temperature is essentially constant with height.

The variation of temperature with height in Earth's lower and middle atmosphere. The dotted horizontal lines indicate the "pauses" while the vertical solid lines indicate the distinction between the lower and middle atmosphere. The upper atmosphere (that is the region above the mesopause) includes the electrically neutral thermosphere and its ionized component, the ionosphere.

The atmospheric temperature profile exhibits three basic heating regions.

  1. The surface, where solar radiation is absorbed by the land and water and transported into the troposphere. This heating is enhanced by the Greenhouse effect.

  2. The stratosphere, where solar ultraviolet radiation is strongly absorbed by ozone.

  3. The thermosphere, where solar radiation is absorbed by O2.

In between are two cooling regions.

  1. The troposphere, the region of the atmosphere which we and most of the rest of the biota inhabit.

  2. The mesosphere, the region of atmospheric cooling between the stratosphere and the thermosphere.

The lidar's laser transmitter fires a beam of light into the sky. A small fraction of this light is scattered back to the receiving telescope. To find out how to obtain a temperature from the back-scattered light, click here.

The figure below shows a night's measurements of temperature by the Purple Crow Rayleigh-scatter Lidar. The shaded blue area shows the variability of the temperature over a night's measurements. This geophysical variability of temperature is much greater than the statistical error of the measurements. The dashed line of the figure shows an average temperature profile for the same geophysical conditions form an empirical atmospheric model. Knowledge of the differences between the measured and model temperatures is important for understanding the dynamics of the atmosphere.

References

  1. Ahrens, C. D., Meteorology Today, 4th edition, West Publishing Co., St. Paul, Minnesota, 1991.
  2. Andrews, D. G., J. R. Holton, and C. B. Leovy, Middle Atmosphere Dynamics, Academic Press, Inc., Orlando, 1987.
  3. Brasseur, G. and S. Solomon, Aeronomy of the Middle Atmosphere, D. Reidel Publishing Company, Dordrecht, Holland, 1984.
  4. Chamberlain, J. W., Theory of Planetary Atmospheres, Academic Press, New York, 1978.
  5. Goody, R. M. and J. C. G. Walker, Atmospheres, Prentice-Hall, Inc., Englewood Cliffs, New Jersey, 1972.
  6. Houghton, J. T., The Physics of Atmospheres, 2nd edition, Cambridge University Press, Cambridge, 1986.
  7. Lutgens, F. K. and E. J. Tarbuck, The Atmosphere: An Introduction to Meteorology, 3rd edition, Prentice-Hall, Inc., Englewood Cliffs, New Jersey, 1986.
  8. McIntosh, D. H. and A. S. Thom, Essentials of Meteorology, Wykeham Publications Ltd., London, 1969.
  9. Moran, J. M. and M. D. Morgan, Meteorology: the Atmosphere and the Science of Weather, 2nd edition, MacMillan Publishing Co., New York, 1989.
  10. Peixoto, J., and A. H. Oort, Physics of Climate, American Institute of Physics, New York, 1992.
  11. Rishbeth, H. and O. K. Garriott, Introduction to Ionospheric Physics, Academic Press, New York, 1969.
  12. Schaefer, V. J. and J. A. Day, A Field Guide to the Atmosphere, Houghton Mifflin Company, Boston, Massachusetts, 1981.
  13. Wallace, J. M. and P. V. Hobbs, Atmospheric Science, Academic Press, New York, 1977.
  14. Wayne, R. P., Chemistry of Atmospheres, Clarendon Press, Oxford, 1991.