Written by Dr. Tim Ball
Few people know that skin is an organ; even fewer know it’s the largest organ of the body. It is the contact, called an interface, between two completely different environments; the body and the world. It controls movement of gases, liquids and solids in both directions all the time. The surface of the Earth is similar as the interface between the atmosphere and the underlying surfaces. Accurate measurement and understanding of processes are critical to what is happening in the atmosphere, under ground and in the oceans. Unless we understand the dynamics across the interface we will not know what is going on above and below the surface.
Science divides the world and its atmosphere into layers depending on what they are studying. For example, geophysicists start in the centre of the Earth with the Solid Inner Core extending through the Liquid Outer Core, the Mantle and the crust. Climate science identifies layers (Figure 1) but even at this point we begin seeing the limitations. The layers are based on energy from the Sun. They ignore volumes of geothermal energy that move through the crust, especially under the oceans where the crust is thinner and more perforated.
Simple, but major, differences between land and water illustrate the problems. Movement of heat from within the earth is different primarily because of circulation. Solar energy penetrates up to 50 meters into the ocean while it hardly penetrates the soil at all. It takes much more energy to raise the temperature of water than land, but it also cools much slower.
Rates of evaporation – that is molecules of water that are given enough velocity by heat energy to escape the surface – are also very different. There is an unlimited supply of molecules in the oceans. Since this is the major source of energy transfer to the atmosphere, it is critical to weather and climate.
Figure 1 shows atmospheric layers. It shows the boundaries (interfaces) above the surface, such as the Tropopause and the Stratopause but leaves out the major critical interface between the atmosphere and the earth. These boundaries separate by temperature, but you can use other measures. The term atmosphere is an example because it encompasses the entire region to the edge of space and is different from the lithosphere and hydrosphere. It also includes the thinnest but most important zone, the biosphere. It is a very narrow zone that contains virtually all life on the planet yet is mostly within a few meters of the surface.