re: Is Water Vapor a Greenhouse Gas? If not what are the implications?

quote:

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If you don't believe water vapor is a greenhouse gas, just step into any greenhouse in the South on a hot summer day.

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First, I'm going by the IPCC's definition of greenhouse gas. By their definition water vapor is ruled out because it provides a negative feedback effect. Despite begin ruled out they still classify water vapor as a greenhouse gas. I don't even know if they are aware of the logical contradiction.

Second, when you measure the heat within a physical greenhouse with well defined boundary conditions you are measuring the heat capacity of the gaseous mixture in the greenhouse.

Even though climate science like to use the "greenhouse" analogy, it's not analogous. The fundamental difference between a greenhouse and the earth's atmosphere is a greenhouse has a defined boundary condition, its walls and roof. The earth's atmosphere boundary condition is infinite.