Quote:
Originally Posted by Karl
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Based on visual inspection (without actual analysis) - these graphs appear to show a trend of higher averages or means
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As an illustration of what I am referring to, look at the "0 degrees" (horizontal axis) either of the two graphs posted by Prasham. Using the "spike" of 1998 as a reference point, the temperatures show fluctuation or oscillation both before and after 1998 - however, what is clearly demonstrated is that prior to 1998 the "fluctuations" showed values that were consistently above and below the zero line, whereas subsequent to 1998, the fluctuation trend showed similar characteristics but were almost entirely above the zero line.
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Another point on the lack of "comparability" between the graphs provided by Bored Wombat and Prasham...
The graphs posted by Bored Wombat show trends related to a "
land - ocean" index while Prasham's second graph shows trends related to the lower
troposphere.These are three separate, albeit (for climatological purposes) closely linked systems - the hydrosphere (water), the lithosphere (land + biomass), and the atmosphere.
For the purpose of temperature classification, the atmosphere has five (5) regions - the troposphere, stratosphere, mesosphere, thermosphere and exosphere. The graph refers to the troposphere - this is the region extending from sea level to the tropopause (which depending on conditions is between 7 km and 17 km above sea level). This is the lowest region of the atmosphere (closest to the ground) and it is within this zone that the biosphere is contained.
As such, while the troposphere is the region with the closest physical relationship to the land and ocean, trends cannot be directly transposed from one medium to the other. This is because each of the three systems has different thermodynamic properties (especially "
heat capacity") and therefore a different response in space and time, to variations in thermal effects. For example, the fact that the sea water has a significantly higher heat capacity results in the sea having a higher thermal inertia than than the other environmental media - i.e., it generally responds more slowly to heating effects, but retains the energy for longer periods (than the air or land).
PS
Feel free to consult the search engine of your choice for clarification of any of the terms or concepts used above...