Saturday, December 17, 2011

How do they measure the average temp of the earth?

To be exact, they would have to have measurements 24 hours per day x 365 days per year x every location on the earth.





Even the average temperature in a single locaction is difficult to measure. It's easy to say the average high is x, but the average annual temp? Do they take the midpoint of the daily highs and lows and assume there is a linear warming and cooling period?





Does anyone know how it's done for the entire earth?|||Obviously, accurate measurements with actual thermometers or thermocouples are limited to mostly populated areas, and limited to recent time periods where records have been kept. If you have an area where a temperature record has been kept for a long time, it's easy to calculate an average, either for a particular season, months, or whole year. These temps are compared to temps derived from thermal infrared satellite data, which are capable of deriving surface temperatures for the entire globe, at least for the last few decades. Going back further than that, they use isotopic composition data from ice cores and shells and corals, etc.

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