The “greenhouse effect” is the blanketing effect of large atmospheric molecules(like carbon dioxide) on infrared radiation which warms the planet.
Greenhouse Gas Demo (4 minute):
As shortwave visible sunlight strikes the surface of the Earth, that which is not reflected back into space is converted into long wave infrared radiation and radiated away as heat which interacts with large moleculed trace gases such as carbon dioxide. This slows down the escape of heat into space and results in higher atmospheric temperatures.
Sunlight is part of the electromagnetic spectrum of photon energy coming from the sun. Except for clouds, dust, etcetera, “visible light” (short waved energy) passes through the atmosphere unimpeded. Infrared light (long waved energy), however, gets entangled with large atmospheric molecules such as carbon dioxide, water vapor and other greenhouse gases. The visible light hits the planet’s surface and is either reflected or absorbed. That which is absorbed becomes heat and is radiated away in every direction as infrared radiation. [You’ve seen thermal pictures of bodies emitting heat energy.]
As the ‘infrared radiation’ is radiated out towards space, the larger atmospheric molecules (carbon dioxide, water vapor, etcetera) interact with this long waved photonic energy. These molecules absorb and reemit the photon energy again and again, thus slowing down the escape of this thermal energy emission. This is the “greenhouse effect”, the blanketing effect of carbon dioxide, etcetera on infrared radiation.
We have a smaller amount of infrared radiation coming directly from the sun and a very large amount of such emanating from the planet’s surfaces.
In regards to the greenhouse effect, atmospheric nitrogen and oxygen molecules are of no consequence because infrared radiation (heat) passes through them as though they weren’t even there. That’s because they’re too small. However, greenhouse gas molecules are large and tangle up long waved infrared radiation.
Note: If you could bring all the clouds and water vapor in the atmosphere to the surface, it would form a ‘liquid’ layer less than an inch deep, and clouds alone would create a layer no deeper than a coat of paint. If just this past year’s carbon dioxide emissions could be confined to an undiluted layer of pure CO2 at the surface of the Earth, the layer would be about 1.5 inches thick (and is growing thicker).
Visible Spectrum of Light:
Infrared Radiation (IR):
As sunlight strikes an object, if it is white (like snow) then the photons mostly reflect off as light back into space. If the color of the surface is darker, then more of the photons are absorbed and converted into heat (infrared radiation). This heat gradually radiates away from the surface of the planet, with the only thing ‘slowing it down’ being the larger air molecules like carbon dioxide, methane, water vapor, etcetera. Molecules like nitrogen and oxygen have no ability to absorb and reemit infrared radiation.
The greenhouse effect is all about Infrared Radiation (IR). It is the ‘heat’ that results from sunlight striking the surface of the planet. As the heat (IR) radiates away from the surface, it interacts with the large molecules present in the atmosphere. Water vapor, carbon dioxide, methane and several other significant gases are examples of such. This interaction slows down the escape of IR out into space. To visualize this, watch the following five second clip that repeats:
If you’ve ever seen ‘heat waves’ shimmering off of a hot asphalt road far ahead of you on a long straight highway, then you have seen ‘infrared radiation’ in action. Infrared radiation (IR) continually radiates heat away from the surface of the Earth. Nitrogen, oxygen and argon gases of the air do not interfere with the passage of IR; but, large molecules like carbon dioxide, methane and such (greenhouse gases) slow down the escape of IR (heat) out into space. Called the ‘greenhouse effect’, it’s like a slowdown on the freeway, with the heat waves getting jammed up — and this causes the air temperatures to rise. This is a natural process. Indeed, if it weren’t for the greenhouse effect, our planet would have always been a frozen ball of ice.
Visible light of the ‘electromagnetic spectrum’ passes through the atmosphere. It strikes and warms the surface of Earth as the result of being converted to infrared radiation (IR). Carbon dioxide and other greenhouse gases absorb and reradiate this heat. It is this heat index that is increased as the volume of greenhouse gases increases in the atmosphere.
The "Greenhouse Effect" is a basic physics phenomenon in which the atmosphere of a planet snares radiation emitted by its sun; that is, the trapping of the sun's warmth in a planet's lower atmosphere due to the greater transparency of the atmosphere to visible radiation from the sun than to infrared radiation emitted from the planet's surface.
Gases such as carbon dioxide, water vapor, methane and other trace gases allow incoming sunlight to pass through, but, retain heat radiated back from the planet's surface.