What is the ratio of energy entering & exiting the atmosphere?

Question

Normally, I believe it is 1:1. How much has it changed with the increased greenhouse gases?

http://eosweb.larc.nasa.gov/EDDOCS/images/Erb/components2.gif

Answer 1

It's still very close to 1.

The amount of energy entering and leaving the top of the atmosphere must be in exact balance, because if it's not, the earth will gain or lose energy. In the current case, the Earth is warming, so the energy leaving must be slightly greater than the energy coming in. But the effect is quite small on the total energy budget.

In outer space, the Sun (at a distance of 1 AU, Earth's average distance) puts out 1365 watts per square meter. A circle the size of the Earth has an area of 1.278 x 10^14 square meters, so the Earth intercepts 1.74 x 10^17 Watts continuously. We assume that energy is spread out over the entire surface of the Earth (which has four times the area of the intercepting circle), so an average square meter on Earth is intercepting 341.25 Watts of solar energy, 24 hours per day. If Earth's temperature were static, each square meter would be emitting exactly the same amount.

The effect of greenhouse gases reduces our energy emissions slightly. Current IPCC estimates put the effect of anthropogenic greenhouse gases at about 1.6 Watts per square meter. That would imply that the energy leaving is roughly 339.65 Watts per square meter. The ratio would then be greater than 99.5%.

Answer 2

Total energy entering the atmosphere is around 300 watts per square metre (distributed over the entire earth). There is energy rising up from the earth's magma which gets radiated into space. The IPCC has estimated that the energy incident on the earth surface (not edge of atmosphere) is 1.6 Watts per square meter more than it was in 1750, but it's a bit hard to convert that into an energy imbalance for the atmosphere.

In short I don't know if anyone knows accuratly what the imbalance is, but the ratio will be pretty close to 1:1

Over a long period of time, the total energy leaving the earth will be more than the total energy absorbed by the earth due to gradual cooling of the earths magma.

Answer 3

You should not give thumbs down to your first answer USDADDY. Water vapor and clouds are more important and more abundant that CO2. Look and read the very important and informative article from Caltech last year (2006)entitled: OUR ATMOSPHERE: THE VIEW FROM ABOVE. (See source below). It contains graphics, including a more detailed "Earth Energy Budget" than yours, and information taken from NASA's Earth Observing System (EOS) of satellites. Man made greenhouse gases amount to a measly 3 watts/square meter of the 342 watts /square meter of the atmosphere's radiation budget.

(It never ceases to amaze me how ignorant some people got to be from listening to liberal arts major Al Gore.)

Answer 4

Correct me if I'm wrong here, but it seems simple to me. Aside from the atmospheric gymnastics that is.

From conservation of energy, it will always move towards 1:1. As greenhouse gasses increase, more heat is trapped and the temp. rises. The earth will then radiate at higher energies to stay in balance, but the balance point will be a new, higher temperature. So, unfortunately, even though we get back to 1:1, it will be hotter.

Here's a example: Two flat plate thermal solar collectors everything being equal except one is painted black and the other is coated with black chrome selective surface. Sun is shining over a period of a few hours at mid day. Drain the working fluid from the collectors. The painted one will stagnate around 200F because as the temp goes up it can re-radiate the heat freely and it escapes back out the glass. The black chrome one will stagnate at 500F because it can't radiate enough energy at the lower temps and has to get hotter before it can start to radiate.

Same input, same move to equilibrium, different temperature.

edit:
This is over complicating things. All things being equal with two collectors painted black. One has one sheet of glazing, the other has two. The one with two sheets of glazing will stagnate at a higher temperature.

And I'll take 1945 in the pool.


Scientific American / Nature
March 15, 2001
More Proof of Global Warming
By Harald Franzen


"Although most scientists are convinced that global warming is very real, a few still harbor doubts. But a new report, based on an analysis of infrared long-wave radiation data from two different space missions, may change their minds. "These unique satellite spectrometer data collected 27 years apart show for the first time that real spectral differences have been observed, and that they can be attributed to changes in greenhouse gases over a long time period," says John Harries, a professor at Imperial College in London and lead author of the study published today in Nature.

As the sun's radiation hits the earth's surface, it is reemitted as infrared radiation. This radiation is then partly trapped by the so-called greenhouse gases: carbon dioxide (CO2), methane (CH4) and chlorofluorocarbons (CFCs)—as well as water vapor. Satellites can measure changes in the infrared radiation spectrum, allowing scientists to detect changes in the earth's natural greenhouse effect and to deduce which greenhouse gas concentrations have changed.

The researchers looked at the infrared spectrum of long-wave radiation from a region over the Pacific Ocean, as well as from the entire globe. The data came from two different spacecraft—the NASA's Nimbus 4 spacecraft, which surveyed the planet with an Infrared Interferometric Spectrometer (IRIS) between April 1970 and January 1971, and the Japanese ADEO satellite, which utilized the Interferometric Monitor of Greenhouse Gases (IMG) instrument, starting in 1996. To ensure that the data were reliable and comparable, the team looked only at readings from the same three-month period of the year (April to June) and adjusted them to eliminate the effects of cloud cover. The findings indicated long-term changes in atmospheric CH4, CO2, ozone (O3) and CFC 11 and 12 concentrations and, consequently, a significant increase in the earth's greenhouse effect. "

Answer 5

1 to 1.
Carbon dioxide amounts to only 3 percent of all greenhouse gases. More important are water vapor and clouds. 342 watts per square meter enter and 342 watts per sqauer meter leave. About 3 watts/m^2 due to man made greenhouse gases. That's less than 1% of earth's total energy budget.

Answer 6

The whole system of energy entering & exiting the atmosphere is known as Earth's Energy Budget and Keith's answer is spot on part from having slightly underestimated the anthropogenic component which is 2.3 to 2.6 Watts per square metre per year.

Answer 7

I've already calculated in several previous answers how many megaTons of TNT a 1 degC rise in ocean temperature is equal to: 1.3 Billion MegaTons. (or 1.3 billion one megaton atom bombs)

1.74 Watts = 1496 calories/hr (lets round it up to 1500)
therefore 1.74 X 10^17 watts = 1500 X 10^17 cal/hr
1 megaTon of TNT = 10^15 calories

1500X 10^17 cal/hr X 24 hr/dy X 7 dy/wk X 52 wk/yr X 1.6/341.25 (ratio from previous poster) / 10^15 cal/MegaTon of TNT = 43 million MT/yr (43 million atom bombs per year)

1300 million/ 43 million = 30 years to get where we are today.

Sounds about right. But of course you have to realize that 100% of that excess energy doesn't end up in the oceans ... So if someone is willing to do better calculations (based on a log curve) you should get an idea when AGW started.

Anyone want to start a pool? I'm guessing around 50 years (I reserve 46 & 54 in the pool)

Answer 8

Keith has it right (and deserves the 10 points), but let me say it simply.

The ratio has to be 1:1. Or the Earth will warm until it is 1:1. But the Earth is warming (slightly but enough to cause serious problems). So the ratio must be a little less right now. Keith's calculations show it's about 1 : 0.995.

We're headed back to 1:1, of course. But if we do nothing, life will be unpleasant by the time we get there.

Answer 9

If you really want to get down to the nitty gritty, you would need to subtract the amount of solar energy used by photosynthesis, this is solar energy that is converted into chemical energy. Also the amount of kinetic energy needs to be subtracted that is generated by convection or wind, which generates ocean waves. A lot of that energy is absorbed by the earth in the form of compressional, shear and rally waves, which leads to coastal erosion.