The average luminance of the Sun is about 1.88 giga candela per square metre, but as viewed through Earth's atmosphere, this is lowered to about 1.44 Gcd/m2. However, the luminance is not constant across the disk of the Sun (limb darkening).
What is it? Greenhouse effect It is a natural phenomenon that occurs on planet Earth. The process is similar to that in a greenhouse used for plant cultivation, but at the planetary level.
How does it work? The atmosphere captures some of the sun's rays that reach the earth's crust, keeping them inside to maintain an approximate temperature of 15 ° C. If the atmosphere does not catch any of these rays that bounce off the surface, the Earth's average temperature would be several degrees below zero. One part of the solar energy is absorbed by the atmosphere, another part is reflected by the clouds, and another part reaches the planet as the visible light that warms us. Once solar radiation has warmed the earth's surface, the earth returns energy, reflecting it and sending it back to the atmosphere.
What are greenhouse gases and how do they relate to the greenhouse effect? The atmosphere is composed of various natural gases. Mostly nitrogen, oxygen and argon. Other gases such as water vapor, carbon dioxide, methane, nitrogen oxide and ozone are those that have a greater impact on the greenhouse effect. Greenhouse gases retain some of this solar energy inside the planet, and do not let it go into outer space. It is this radiation, which cannot escape the planet, that causes the surface temperature to rise.
Why is the greenhouse effect important to life on Earth? It is a very important process thanks to which the temperature of the planet is regulated to make life possible, allowing to maintain an adequate and pleasant temperature for living beings, retaining part of the sun's energy and releasing another part towards space.
