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Chris Ho-Stuart
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Here now is version 2 of the spreadsheet. To download, click on this link.

This version now considers convection within a grey atmosphere. The file is actually hosted at a free file hosting service, rather than being provided as a post attachment, since it is a bit bigger than the attachment limit. The following changes will be apparent from version 1.

  • On the first worksheet (definitions) we have as before a column marked "Inputs", where there are green cells in which values can be entered; and a column marked "Values", where all values in use are recorded. There is now also an additional column marked "%change", which gives the difference between values recorded in the default example planet and the values calculated. This makes it easy to alter one input, and observe all the consequences on other values.
  • As inputs and values, temperatures are given in Celsius, and pressure in atmospheres, without using additional rows for the SI units actually used in calculations.
  • In the green input cells in the definitions worksheet, you can enter text of form "*###", where ### is a number. This uses the default number multiplied by that number. For example, "*1.1" will use as the input the default value increased by 10%. The resulting actual value used appears in the "Values" column.
  • The formatting of the "Integration" work sheet is cleaned up a lot, to be informative for those who want to follow the integration calculation. It also provides some green input cells where users can override the values carried forward from the definitions sheet; useful (to me!) for debugging the integration; and hence probably useful to others as well who want to delve into the details or make modifications. These input cells should all be cleared for the integration to properly represent the inputs from the definitions sheet. There are warnings supplied, on both worksheets, when such overriding is in place.
  • Calculations for a constant lapse rate throughout the entire atmosphere are still available. As well, there is a calculation of the energy imbalance at each layer of the atmosphere considered. In the troposphere, the atmosphere tends to lose more energy by radiation than it gains. The difference is made up by convection, which supplies additional energy needed to maintain the lapse rate. The integration worksheet gives backradiation, cooling rates and convection at each level of the atmosphere, under the constant lapse rate assumption. A negative cooling rate indicates a breakdown of the assumptions under which the adiabatic lapse rate is stable. This is characteristic of the atmosphere above the tropopause.
  • The integration is now extended with a new calculation that identifies where the tropopause appears, and adjusts the calculation method above that point to be a radiative equilibrium. Rows of the integration worksheet are shaded light blue above the tropopause. Note that the constant lapse rate assumption locates the tropopause differently from the more accurate calculation! This shows up in the shading as well.
  • As for version 1, the lapse rate row also accepts the text "DALR", which uses the dry adiabatic lapse rate as the lapse rate.
  • Some minor changes in appearance; fonts, layout, colors, etc. (This version should load better into older versions of Excel.)
  • There are changes in the internal coding, which do not materially alter the behaviour other than what is mentioned above; with the exception of the bug fix, mentioned previously for calculating the effective emission temperature.

I'm doing a bit of double checking that the coding is all correct; but in any case, here it is. If anyone finds bugs or errors I'll be very glad to hear of it.

Edited by Chris Ho-Stuart, Dec 19 2011, 02:09 AM.
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The giant space ship example · Physical theory for climate