The sun is the central energy source of the Earth’s entire climate system. Nearly all atmospheric processes — temperature distribution, air pressure differences, wind circulation and the global water cycle — are driven exclusively by incoming solar energy.
Without the continuous energy input from the sun, there would be neither wind nor precipitation. All weather phenomena are ultimately a consequence of the uneven heating of the Earth's surface by solar radiation.
This makes it clear: the Earth's climate system is primarily a dynamic flow system controlled by solar energy.
How much energy from the sun reaches the Earth?
The radiative power at the surface of the sun is about 63,000 kW/m².
At the top of the Earth’s atmosphere, the average solar radiation is approximately
1,365 W/m²
This value is known as the solar constant. Because the Earth is spherical and only one hemisphere is illuminated at a time, this energy is distributed across the entire surface of the planet. The highest radiation occurs near the equator and the lowest at the poles. In addition, about 30 % of the incoming energy is reflected by clouds, ice surfaces and bright ground (albedo).
Globally averaged, only about
240 W/m²
remain as actually absorbed solar energy.
Part of this energy drives photosynthesis, while another part heats the Earth's surface, the oceans and the atmosphere, thereby driving all dynamic processes in the climate system.
How much energy reaches the Earth per hour?
The surface area of the Earth is
AE = 5,067 * 1014 m²
Multiplying this area by the average radiation PE = 240 W/m² results in a global power of
1,216 * 1017 W
Over one year this corresponds to an energy amount of approximately
3,835 * 106 EJ (Exajoule).
Per hour, the average energy input from the sun to the Earth is therefore approximately
438 EJ
This continuously flowing amount of energy is enormous.
For comparison:
The total energy consumption of humanity, about 650 EJ per year, is extremely small in comparison (factor 5,900). The amount of solar energy arriving per hour corresponds to about 68% of global annual energy consumption.
Therefore, direct anthropogenic energy input plays practically no role compared to solar energy input. The decisive factor for the climate is not additional human energy, but the distribution of existing solar energy within the atmospheric system.
Only a very small part becomes wind
Only a small fraction of incoming solar energy is converted into kinetic energy of the atmosphere. Estimates suggest that only about
1–2% of solar energy
is converted into kinetic energy of air masses. Part of this energy drives vertical convection or is dissipated through waves and friction.
For large-scale horizontal wind systems, only about
0.5–1% of the original solar energy
However, this seemingly small amount of energy has a central importance: it drives large-scale air circulation that transports heat and moisture across the planet remains.
Wind as a central climate regulator
Wind is the mechanism that distributes the energy introduced by the sun. It transports heat from the tropics to higher latitudes and moisture from the oceans to the continents.
Thus, atmospheric circulation controls the global water cycle. Without these air movements, extreme temperature differences and massive precipitation imbalances would develop.
Wind is therefore an essential component of the natural climate equilibrium.
More on this on the pages Wind Energy and Global Water Cycle.
The page "Using Solar Energy" explains how solar energy can be used as effectively as possible.
