This STELLA diagram visually represents the planetary climate model by categorizing key climate-related variables into three main groups: Energy In (yellow area), Temperature (red area), and Energy Out (blue area).
- Energy In (Yellow Area):
- Factors affecting incoming solar energy: Solar Constant, Albedo, Surf Area.
- These variables influence Insolation, which directs energy to Earth Heat.
- Temperature (Red Area):
- Includes Ocean Depth, Water Density, and Heat Capacity, which influence Temperature.
- Temperature interacts with Earth Heat and contributes to heat exchange processes.
- Energy Out (Blue Area):
- Outgoing energy factors include Heat Emitted, LW Int, and LW Slope.
- Earth Heat emits energy, balancing the system.
Arrows show the flow of energy and interactions between these factors. The diagram helps illustrate the components regulating planetary climate.
The Energy In sector (yellow in Fig. 1 above) controls the amount of insolation absorbed by the planet. The Solar Constant is not really a constant, but it does tend to stay close to a value of 343 Watts/m2 (think of about six 60 Watt light bulbs shining down on a patch of ground 1 meter on a side — this is what we get from the Sun). This is then multiplied by (1 – albedo) and then the surface area of the Earth giving a result in Watts (which is a measure of energy flow and is equal to Joules per second). In the form of an equation, this is:
S is the Solar Constant (343 W/m2), A is surface area, and α is the albedo (0.3 for Earth as a whole).
This is the equation