The layer model that we constructed in Chapter 3 did not have convection. Think about a layer model with multiple atmospheric layers, such as one constructed in Project 2 in Chapter 3. The temperatures of the layers decrease with altitude, just like the real atmosphere does, but the only way that heat is carried between the layers in the layer model is by blackbody radiation. One could construct a model with a continuous atmosphere, with temperature varying smoothly with altitude like the real atmosphere, but where radiation is the only way of moving heat. The temperature profile you would get from a model like this is known as radiative equilibrium. Radiative equilibrium controls the temperature structure inside some stars and would control the temperature profile in the Earth's atmosphere, except that convection kicks in first. A radiative equilibrium lapse rate in our atmosphere would be about 16 K/km of altitude, so steep that it would be convectively unstable.
If we were to try to add convection to the layer model, we would have to add another set of heat flow arrows to the model, representing the heat carried by air as it ascends, and by water vapor as it condenses releasing latent heat. We are not going to create such a model, but Fig. 5.10 gives an impression of how it might look. Convection might insist that the temperature of layers aloft must follow a moist adiabat, roughly 6 K/km of altitude. The state of energy balance when both radiation and convection are taking place is called radiative-convective equilibrium.
Was this article helpful?
Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.