How much of the sunlight does earth receive?

Question

What percentage of the sun's total sunlight or energy does the earth receive during a typical day? A range would be fine? Is it less than 1% or could it be greater than 30% -typcially.?

Answer 1

Best Answer - Chosen by Asker

MistWing got the numbers wrong. Earth receives one part in 2.2 billion of the radiation emitted by the sun.

Here's how to calculate this.

Let
r = radius of earth = 4000 miles
R = earth-sun distance = 93,000,000 miles

area of sun-centered sphere at earth's location = 4*pi*R^2
cross-section of earth for absorbing radiation = pi*r^2

ratio = 4*(R/r)^2 = 2.2 billion

So the amount of sunlight that reaches the earth is
0.00000005%
of the sun's total luminosity.

Once the sunlight reaches the earth, some is reflected by the atmosphere and some is absorbed by the atmosphere. According to
http://www.starhop.com/Middle/EnPath-10a…
9% is reflected by the atmosphere and 22% is absorbed by the atmosphere.

Thus, of the sunlight that reaches the outer atmosphere of earth, about 69% reaches the surface of the earth. This energy is available for use in solar panels. (Solar panels are much less than 100% efficient, so they produce considerably less than 1 watt of power for every watt of sunlight.)

(I'm not sure exactly how precise this number 69% is. Maybe it's 60%, maybe it's 70%, but it's somewhere in that ballpark.)

The percentage of sunlight that passes through the atmosphere varies with wavelength. In visible wavelengths, most light gets through the atmosphere. In ultraviolet, most is absorbed (but enough still gets through to produce sunburn).

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Asker's Comment:

Thanks so much!! Great answer.

Answer 2

Since we occupy less than one percent of the surface area of the sun we receive far less than 1% of its energy; however that is enough.

According to Wikipedia: http://en.wikipedia.org/wiki/Solar_energ…
"Earth receives 174 petawatts of incoming solar radiation (insolation) at the upper atmosphere at any given time. When it meets the atmosphere, 6 percent of the insolation is reflected and 16 percent is absorbed. Average atmospheric conditions (clouds, dust, pollutants) further reduce insolation traveling through the atmosphere by 20 percent due to reflection and 3 percent via absorption. These atmospheric conditions not only reduce the quantity of energy reaching the earth's surface, but also diffuse approximately 20 percent of the incoming light and filter portions of its spectrum. After passing through the atmosphere, approximately half the insolation is in the visible electromagnetic spectrum with the other half mostly in the infrared spectrum (a small part is ultraviolet radiation)."

According to Wikipedia: http://en.wikipedia.org/wiki/Watt#SI_mul…
a petawatt is 1 x 10^15 watts.
a zettawatt is 1 x 10^21 watts.

The article continues:
"- The total solar energy available to the earth is approximately 3850 zettajoules (ZJ) per year.
- Oceans absorb approximately 285 ZJ of solar energy per year.
- Winds can theoretically supply 6 ZJ of energy per year.
- Biomass captures approximately 1.8 ZJ of solar energy per year.
- Worldwide energy consumption was 0.471 ZJ in 2004."

Wind is created when sunlight heats the land and causes warm air to rise. Air currents are created because things are colder at the poles than at the equator and some areas of the earth are warmer than others (like the Pacific Ocean off of South America during El Nino conditions).

According to Wikipedia: http://en.wikipedia.org/wiki/Sun
"The sun has a surface area of 6.088×1018 m²." At 93 million miles away the shadow that the earth would cast upon the sun would be so tiny that it would be a mere dot; so 99.9999% of the sun’s energy is radiated off into space. The planets surface are combined probably don’t consume even 1% of the energy radiated from the sun.

Answer 3

remember that the suns rays spread out in every direction, and we are 93 million miles away. Out of all of the sunlight that the sun produces, I would estimate we receive less than .001% of the suns total output. It is probably even a lot less than that.

Answer 4

If I calculated it correctly, 1 part in 46 billion... much less than 1 percent.