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How the Greenhouse Effect Traps Heat and Warms Earth


Greenhouse Effect

I’ve good news and bad news about the greenhouse effect.

First, the good news:

JUST RIGHT: Because greenhouse gases trap heat in the atmosphere, this helps regulate temperature on Earth. Without greenhouse gases, we’d live in an icebox. It would kind of be like living on the moon which doesn’t have an atmosphere at all.

Now, the bad news:

EXCESS: Because we put too much CO2, methane and N2O in the air, it amplifies the greenhouse effect and less solar radiation is radiating back to space. As we should know, too much of a bad thing can leave everlasting consequences for our planet.

We need the greenhouse effect

Greenhouse Effect

A greenhouse is usually something useful. For example, we build a greenhouse to grow tomatoes out of season. It’s warm in a greenhouse because sunlight enters and traps in heat.

  • Visible light passes through the glass. Plants and soil absorb the solar radiation and warms it. On the other hand, some sunlight is partly reflected back to the outside, never fully entering inside the greenhouse.
  • For the infrared radiation that enters the greenhouse, some of it partly bounces off the surface and exits into the atmosphere. But when infrared radiation is re-emitted within the greenhouse, it traps heat and warms inside the greenhouse. And this is where the greenhouse effect comes into play.

On Earth, if we didn’t have greenhouse gases, we’d live in an icebox. It would kind of be like living on the moon which doesn’t have an atmosphere at all.

If you compare temperatures on the moon, it’s much colder. Even though distance to the moon is similar for Earth and the sun, the difference is that Earth has an atmosphere. Overall, temperatures would be about 9 to 10°C colder if it wasn’t for the greenhouse effect.

But we don’t need too much of the greenhouse effect

Now, the bad news. Human activity is driving temperature up. We add greenhouse gases like methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2O) in a large part due to agricultural activity and burning fossil fuels. Because we put too much of it in the air, it amplifies the greenhouse effect and less solar radiation is radiating back to space. In general, temperatures are increasing as a whole for the entire planet.

For example, if we look outside our solar system we can see how the greenhouse effect alters temperature on other planets.

Venus receives nearly twice as much sunlight as Earth because it’s much closer to the sun. But it’s because 96.5% of Venus atmosphere is carbon dioxide, the greenhouse effect is in full effect on Venus. It’s the hottest planet due to this fact.

Like Earth, sunlight heats the surface. But the heat is contained because of the Venusian clouds and carbon dioxide prevents it from escaping. This is why surface temperature reaches 460°C on Venus which is hot enough to melt lead.

Annual greenhouse gas index


  1. According to a scientist, there are only three known ways that solar radiation is observed every day to heat Earth’s atmosphere. The first is by conduction when air touches Earth’s sun-warmed surface and the warmed air rises. This is how air is heated above a hot frying pan. And this is how the troposphere, the lowest layer in Earth’s atmosphere, where we live, is heated from below when sunlight is available.

    Temperature in the troposphere decreases with increasing altitude up to the tropopause, the boundary between the troposphere heated from below by conduction and the stratosphere heated from above by solar radiation. The tropopause is normally at an altitude close to 11 miles above the tropics, but only 5.6 miles above polar regions with temperatures typically 130 cooler than Earth’s surface. Airplanes normally fly near the top of the troposphere.

    The second way air is heated is by dissociation. Dissociation primarily of molecular oxygen causes the top of the stratosphere, at altitudes of around 32 miles, to be 106 warmer than the tropopause at the base of the stratosphere. When a molecule of oxygen, containing two atoms of oxygen absorbs solar ultraviolet-C radiation, the molecular bond is dissociated, which means broken apart. The two oxygen atoms fly apart at high velocity just like the ends of a snapped rubber band. Air temperature is proportional to the average velocity of all atoms and molecules in the air squared. In this way, dissociation turns chemical bond energy directly and efficiently into air temperature.

    Then, two atoms of oxygen can collide without reducing air temperature and be dissociated again, making the air warmer and warmer in a cycle that continues until all solar ultraviolet-C radiation has been absorbed before it reaches the base of the stratosphere.

    Similarly, a molecule of ozone, containing three oxygen atoms, is dissociated when it absorbs solar ultraviolet-B radiation. The atom of oxygen and the molecule of oxygen fly apart at high velocity, warming the ozone layer. They can recombine by collision and then be dissociated again in a cycle that continues until all solar ultraviolet-B radiation has been absorbed.

    Normally, nearly all solar ultraviolet-B radiation is absorbed in the ozone layer. But when the ozone layer is depleted by some chemical process, less ultraviolet radiation is absorbed in the ozone layer, cooling the ozone layer. More ultraviolet-B radiation is observed to reach Earth where it dissociates ground level ozone pollution, warming polluted air in urban and industrial areas.

    The third way air is heated is by ionization that only occurs in the ionosphere, located above the stratosphere. Very high-energy solar radiation separates electrons from atoms and molecules. The pieces fly apart at high velocity, warming the ionosphere.

    “But there is another process active in urban areas, the dissociation of ozone which has been widely ignored” says Dr. Peter L. Ward, a geophysicist who worked 27 years with the U. S. Geological Survey when presenting his conclusions at the annual meeting of the American Geophysical Union (AGU) on December 15.

    Ozone is the main chemical ingredient of smog in urban areas. Ground-level ozone pollution is created by chemical reactions between oxides of nitrogen and volatile organic compounds. These reactions are common when pollutants emitted by cars, power plants, industrial boilers, refineries, chemical plants, and other sources react chemically in the presence of sunlight. Ozone pollution damages lungs, irritates throats causing coughing and shortness of breath, and can cause chest pain.

    “It turns out,” Ward explains in his presentation, “that no physical way has even been demonstrated for air to be warmed when greenhouse gases absorb infrared radiation from Earth, which does not have enough energy to dissociate or ionize anything.”

    The ozone layer is especially important for life on Earth because it normally absorbs most ultraviolet-B radiation that has enough energy to cause sunburn, skin cancer, cataracts, and mutations. Since 1970, you have been at higher risk for these problems.

    In the 1960s, manufactured chlorofluorocarbon gases (CFCs) became widely used as spray-can propellants, refrigerants, solvents, and foam blowing agents. Ozone depletion and average global surface temperatures began increasing. In 1974, scientists discovered that CFCs can be broken down by ultraviolet radiation in the stratosphere, freeing atoms of chlorine, and that one atom of chlorine, under the right conditions, can destroy 100,000 molecules of ozone. This work earned the Nobel Prize in Chemistry in 1995.

    The United Nations passed the Montreal Protocol on Substances that Deplete the Ozone Layer, severely restricting production of CFCs beginning in 1989. By 1993 the increase in atmospheric concentrations of CFCs stopped. By 1995, the increase in ozone depletion stopped. By 1998, the increase in global temperatures stopped. Humans caused the world to warm 1.1 from 1975 to 1998. Humans then stopped the warming by passing the Montreal Protocol.

    “Without the Montreal Protocol,” Ward explains, “Earth would probably be at least 0.5 warmer today. CFCs are very stable substances. Unfortunately, it will take decades for the ozone layer to recover. Meanwhile temperatures will remain warm in urban areas.”

    Ward concludes “ozone depletion played a major role in global warming since 1970 and can explain quite directly why urban areas are warmer than rural areas.”


  2. Why don’t we use CO2 to insulate our windows should be perfect after reading on your web-site.

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