Lasted edited by Andrew Munsey, updated on June 14, 2016 at 9:20 pm.
The true nature of global warming?
'Author argues that the ozone depletion plays a larger role in global warming than elevated CO2 levels.'
Compiled by Steve Gage, October 2008
What is ultraviolet radiation?
Ultraviolet radiation is one form of radiant energy coming from the sun. The various forms of energy, or radiation, are classified according to wavelength, measured in nanometres (one nm is a millionth of a millimetre). The shorter the wavelength, the more energetic the radiation. In order of decreasing energy, the principal forms of radiation are gamma rays, X rays, UV (ultraviolet radiation), visible light, infrared radiation, microwaves, and radio waves. There are three categories of UV radiation:
UV-A, between 320 and 400 nm
UV-B, between 280 and 320 nm
UV-C, between 200 and 280 nm
Heat is the total energy associated with random atomic and molecular motions of a substance. Heat is transferred in three ways. Radiation is the transfer of energy via electromagnetic waves. Radiation does not need an intervening medium to pass heat energy from the emitter to the absorber. When radiation from the Sun is absorbed by the Earth it does work by setting molecules in motion and raising their kinetic energy level. In a solid, the molecules may vibrate more rapidly and collide with one another and transfer heat from warmer to colder portion of the mass by conduction. In fluids like air and water, heat is transferred by the circulation of molecules via the process of convection.
The "Greenhouse Effect"
The actual flow of heat is complicated by the atmosphere, which has three strong effects:
Clouds in the atmosphere reflect some of the sunlight before it reaches the ground, reducing the heating of the ground. This process, hard to estimate, has been monitored by measuring "earthshine", the faint glow from the dark part of the Moon when only a thin crescent is visible.
The atmosphere absorbs the infra-red (IR) light radiated from the ground and thus delayes the escape of heat to outer space, keeping the ground warmer than it would otherwise be.
Air can flow, and thus carry its heat from one place to another. That is what produces our weather. The 3rd process is discussed further below. It is a big subject--made even bigger by the influence of water vapor, which produces rain, hurricanes and other interesting phenomena--and two additional sections are also devoted to it, starting here.
The second process (which keeps us warmer) is stronger than the first (which reduces warming), so the net effect is that like a blanket, the atmosphere helps keep Earth warmer than it would be otherwise. This is called the "greenhouse effect," because the same process operates in greenhouses used for growing vegetables in cold climates. A greenhouse is enclosed and roofed by glass panes, which let sunlight enter, but absorb the IR emitted back by the ground, and thus keep the greenhouse warm. The chief absorbers of IR in the atmosphere are not nitrogen and oxygen, the main constituents of air, but a relatively minor percentage of "greenhouse gases" such as water vapor (H2O), carbon dioxide (CO2) and methane (CH4), which are strong absorbers of IR. Another molecule, responsible for an important effect even though only a very small amount of it is present, is ozone, a variant of the oxygen molecule--O3 rather than the usual O2. It is produced at high altitudes by the action of sunlight on ordinary oxygen and its peak concentration is around 25 kilometers. It is also a greenhouse gas, but more important, it absorbs the Sun's ultra-violet (UV) light, which can cause skin burns and hurt eyes. The ozone found near the ground and forming part of the urban air pollution comes from a completely different process.
The strospheric Ozone layer has depleted, via certain components of our emissons, by 16% over the last four decades. ALL electromagnetic radiation has energy. Ozone depletion lets more UV light through, hiting surface and converting to HEAT. Greenhouse gasses trap part of that heat. But the real culprit is not an increase in CO2, as the increase in the industrial age is miniscule, up 30% to a WHOPPING .03% of total atmosphere [big deal whoopee]. CO2 is nothing but a TRACE ELEMENT in the air. The real culprit is the additional UV light, converting to HEAT when it hits the surface. Too much UV light damages life forms, both plant and animal. Thus, today you will get a sunburn much easier and faster than decades ago. WE DO NOT NEED TO REMOVE CO2 FROM THE AIR, WE NEED TO REPAIR THE OZONE LAYER. [R U listening Al Gore?!]
CO2 is at lowest level since 300 million years ago. http://geocities.com/behindbarsbimbo/co2levels.html