Earth's Solar GreenhouseThe Solar Greenhouse EffectThe solar greenhouse effect is the warming of the planet caused by too much heat from the sun being trapped by the atmosphere. This is a complex situation that requires some clear explanations. Follow the links in the text of this page to gather more information. Energy From the SunThe Sun emits energy in the form of light. This energy comes from fusion reactions between hydrogen nuclei. In these reactions, mass is lost and that mass is transformed into light energy. The sun also produces heat, but we are so far away from it here on earth that we cannot feel that heat. The sun produces light and heat in much the same way as an incandescent (old fashioned) light bulb; it gets hotter and hotter until it glows. The bulb is very hot, but it is the light, not the heat, that travels to the far corners of the room.Mercury: No Atmosphere
If the earth had no atmosphere like Mercury, the planet with no atmosphere, sunlight would fall directly on the surface of the planet. Much of it would be reflected and some would be absorbed. That absorbed light energy will then have changed wavelength to be heat energy, and this heat energy would be radiated back into space. Once the sun stopped shining on the surface it would rapidly cool.
Venus: a Super Thick Atmosphere
Venus the planet is an example of a runaway greenhouse effect. With a dense atmosphere trapping almost all the heat that reaches the planet, there is no hope of liquid water ever forming to cool the surface from its present hellish condition.Venus' remarkable similarities to Earth in terms of size, mass and location in the so-called "habitable zone" around the sun give even more impetus for us to consider it's atmosphere and ensure our own planet does not end up in the same condition. Earth's Atmosphere
Earth's atmosphere acts to reflect some of the sunlight falling on it. It also acts to retain some of the heat energy radiated from the planet with the overall effect of maintaining on average a 15 degree celsius surface temperature.Unlike the other two terrestrial planets in the habitable zone around the sun, Earth's atmosphere naturally only contains a small percentage of Carbon Dioxide, with the bulk being made up of Oxygen gas (O2) and Nitrogen gas (N2). While small, the proportion of CO2 in the atmosphere has a significant impact on the surface conditions of our planet. A little mentioned jet major contributor to the Earth's greenhouse effect is water vapour (excluding clouds). Water vapour accounts for up to 70% of the Earth's heat retention while being in much lower quantities in the atmosphere than Carbon Dioxide. Both water vapour and carbon dioxide sources need to be considered as major greenhouse factors. Mars' Thin Atmosphere
Mars has a very thin atmosphere consisting mainly of Carbon Dioxide. The pressure of the atmosphere, which can also be thought of as the density of the air, is less than 1% of that on Earth. This means that liquid water cannot form on the vast majority of the surface, as it will instantly vaporize. The thin atmosphere is also being stripped away slowly by the solar wind, as Mars does not have a sufficient magnetic field to deflect the charged solar particles.Despite the discovery of vast quantities of frozen water on and near the surface of mars, the state of the atmosphere coupled with the planet's lighter mass and low magnetic field do not make it a good candidate for colonization. While a solar greenhouse effect could possibly be encouraged, the effort and resources required to achieve this would be immense.
Titan: Hydrocarbon World
Titan is Saturn's second largest moon. Its size, possession of an atmosphere and physical characteristics make Titan moon very similar to Earth while also being radically different. The vast quantities of hydrocarbons present on Titan cast doubt on conventional theories of oil formation on Earth.
The Greenhouse EffectThe Greenhouse Effect is the trapping of extra sunlight, converted into heat energy, by the additions we have made to the atmosphere. The effect of molecules like carbon dioxide and methane in this regard are well known. Other gases such as Nitrogen Trifluoride, (learn more about the Lewis Dot structure of NF3) Sulfur Hexafluoride and Hexafluoroethane also contribute to the issue to varying degrees.The major carbon dioxide contribution we humans make come from burning fossil fuels, a process that with some concerted effort and current technology could be eliminated. Large scale solar power plants currently in use and future solar energy projects need to be given greater prominence if we are to tackle this solar greenhouse issue in a serious way. Understanding the way the greenhouse effect works can motivate us to take targeted action to prevent it. We need to ensure that our planet does not become a solar greenhouse on a massive scale. The more facts we have at hand about our impact on the planet, the more awareness we will have in our daily lives. This will help us to make small but important changes in the way we live to minimize global warming, or more correctly climate change, and thus build a better world for our children. |
