The Earth receives energy from the Sun in the form of radiation. Most of the energy is in visible wavelengths and in infrared wavelengths that are near the visible range (often called "near infrared"). The Earth reflects about 30% of the incoming solar radiation. The remaining 70% is absorbed, warming the land, atmosphere and ocean.
For the Earth's temperature to be in steady state so that the Earth does not rapidly heat or cool, this absorbed solar radiation must be very closely balanced by energy radiated back to space in the infrared wavelengths. Since the intensity of infrared radiation increases with increasing temperature, one can think of the Earth's temperature as being determined by the infrared flux needed to balance the absorbed solar flux. The visible solar radiation mostly heats the surface, not the atmosphere, whereas most of the infrared radiation escaping to space is emitted from the upper atmosphere, not the surface. The infrared photons emitted by the surface are mostly absorbed in the atmosphere by greenhouse gases and clouds and do not escape directly to space.
The reason this warms the surface is most easily understood by starting with a simplified model of a purely radiative greenhouse effect that ignores energy transfer in the atmosphere by convection (sensible heat transport, Sensible heat flux) and by the evaporation and condensation of water vapor (latent heat transport, Latent heat flux). In this purely radiative case, one can think of the atmosphere as emitting infrared radiation both upwards and downwards. The upward infrared flux emitted by the surface must balance not only the absorbed solar flux but also this downward infrared flux emitted by the atmosphere. The surface temperature will rise until it generates thermal radiation equivalent to the sum of the incoming solar and infrared radiation.
But the temperature of the atmosphere generally decreases with height above the surface, at a rate of roughly 6.5 °C per kilometer on average, until one reaches the stratosphere 10–15 km above the surface. (Most infrared photons escaping to space are emitted by the troposphere, the region bounded by the surface and the stratosphere, so we can ignore the stratosphere in this simple picture.) A very simple model, but one that proves to be remarkably useful, involves the assumption that this temperature profile is simply fixed, by the non-radiative energy fluxes. Given the temperature at the emission level of the infrared flux escaping to space, one then computes the surface temperature by increasing temperature at the rate of 6.5 °C per kilometer, the environmental lapse rate, until one reaches the surface. The more opaque the atmosphere, and the higher the emission level of the escaping infrared radiation, the warmer the surface, since one then needs to follow this lapse rate over a larger distance in the vertical. While less intuitive than the purely radiative greenhouse effect, this less familiar radiative-convective picture is the starting point for most discussions of the greenhouse effect in the climate modeling literature.
Friday, January 23, 2009
Wednesday, January 21, 2009
Global Warming
Global Warming is defined as the increase of the average temperature on Earth. As the Earth is getting hotter, disasters like hurricanes, droughts and floods are getting more frequent.
Over the last 100 years, the average temperature of the air near the Earth´s surface has risen a little less than 1° Celsius (0.74 ± 0.18°C, or 1.3 ± 0.32° Fahrenheit). Does not seem all that much? It is responsible for the conspicuous increase in storms, floods and raging forest fires we have seen in the last ten years, though, say scientists.
Their data show that an increase of one degree Celsius makes the Earth warmer now than it has been for at least a thousand years. Out of the 20 warmest years on record, 19 have occurred since 1980. The three hottest years ever observed have all occurred in the last eight years, even.
But it is not only about how much the Earth is warming, it is also about how fast it is warming. There have always been natural climate changes – Ice Ages and the warm intermediate times between them – but those evolved over periods of 50,000 to 100,000 years.
A temperature rise as fast as the one we have seen over the last 30 years has never happened before, as far as scientists can ascertain. Moreover, normally the Earth should now be in a cool-down-period, according to natural effects like solar cycles and volcano activity, not in a heating-up phase.
It's not that I want people to disappear. I got rid of human beings theoretically to see how nature would respond without having to deal with us constantly heaping more abuse on the planet. Ultimately, the aim is to figure out if there is a way to add humans back into the mix so that we could live in harmony with nature as opposed to mortal combat with it.
The problem with environmental books, as brilliant as they often are, is that they are so depressing and scary that only environmentalists read them. I wanted to write something that would reach a huge audience, but still be realistic. I wasn't going to pull any punches.
The latest report from the Intergovernmental Panel on Climate Change delivered a huge blow to global warming skeptics. Leading climate scientists are now 90 percent sure that human activity is heating up the planet. They present various scenarios that show where global warming could take us by the end of the century. The choice is ours.
In conclusion, global warming is a very serious problem affecting us all. The scientific community is unanimously convinced that it is the result of human activity, in particular, the release of greenhouse gases caused by burning fossil fuels. Global warming cannot be stopped entirely, but its potential damage can be minimized by lessening our dependence on fossil fuels. We need to change our lifestyles in order to protect our children and grandchildren and leave them a world they can be proud of!
Over the last 100 years, the average temperature of the air near the Earth´s surface has risen a little less than 1° Celsius (0.74 ± 0.18°C, or 1.3 ± 0.32° Fahrenheit). Does not seem all that much? It is responsible for the conspicuous increase in storms, floods and raging forest fires we have seen in the last ten years, though, say scientists.
Their data show that an increase of one degree Celsius makes the Earth warmer now than it has been for at least a thousand years. Out of the 20 warmest years on record, 19 have occurred since 1980. The three hottest years ever observed have all occurred in the last eight years, even.
But it is not only about how much the Earth is warming, it is also about how fast it is warming. There have always been natural climate changes – Ice Ages and the warm intermediate times between them – but those evolved over periods of 50,000 to 100,000 years.
A temperature rise as fast as the one we have seen over the last 30 years has never happened before, as far as scientists can ascertain. Moreover, normally the Earth should now be in a cool-down-period, according to natural effects like solar cycles and volcano activity, not in a heating-up phase.
It's not that I want people to disappear. I got rid of human beings theoretically to see how nature would respond without having to deal with us constantly heaping more abuse on the planet. Ultimately, the aim is to figure out if there is a way to add humans back into the mix so that we could live in harmony with nature as opposed to mortal combat with it.
The problem with environmental books, as brilliant as they often are, is that they are so depressing and scary that only environmentalists read them. I wanted to write something that would reach a huge audience, but still be realistic. I wasn't going to pull any punches.
The latest report from the Intergovernmental Panel on Climate Change delivered a huge blow to global warming skeptics. Leading climate scientists are now 90 percent sure that human activity is heating up the planet. They present various scenarios that show where global warming could take us by the end of the century. The choice is ours.
In conclusion, global warming is a very serious problem affecting us all. The scientific community is unanimously convinced that it is the result of human activity, in particular, the release of greenhouse gases caused by burning fossil fuels. Global warming cannot be stopped entirely, but its potential damage can be minimized by lessening our dependence on fossil fuels. We need to change our lifestyles in order to protect our children and grandchildren and leave them a world they can be proud of!
Monday, January 12, 2009
Tuesday, January 6, 2009
Israel Aggression on Palestinian People
Well If you got power then you should know your limit. If someone who dont know his/her limit like Israel then the consequences will be bear by the Palestinian. Who supporting and gave him suchh power evry body know all about. But no one has the right to attack civilian in such a brutal way and kill innocent people.
Why such things happend because Palestinian people are less powerfull, no regular army and dont have modern and latest weopened for self defence. If they have then you think Israel will attack on them, Never......Ever........
But there are some forces and even super power who still supporting Israel aggression on Palestine people. And all world are watching the show of Israeli airforce and Tanks. No one even bother to do something for Palestine people. UN is helpless and democratice forces who wants democracy all over the world and peace are watching the brutality and aggression of Israel.International media and Human rights agencies are not doing much for the Palestine People in the same way.
No one have sympathy with Palestinian? why?
I request to all Muslim Ummah and internatiopnal Communities to do much and demand for early seize fire from Israel. And they have to put pressure on the Israel for immediate seize fire from one side immediately.
I think if we are fail to do so then Palestine civilian faced much Casualities and losses. And it will enhance Muslim people anxiety and anger in lang run..
Why such things happend because Palestinian people are less powerfull, no regular army and dont have modern and latest weopened for self defence. If they have then you think Israel will attack on them, Never......Ever........
But there are some forces and even super power who still supporting Israel aggression on Palestine people. And all world are watching the show of Israeli airforce and Tanks. No one even bother to do something for Palestine people. UN is helpless and democratice forces who wants democracy all over the world and peace are watching the brutality and aggression of Israel.International media and Human rights agencies are not doing much for the Palestine People in the same way.
No one have sympathy with Palestinian? why?
I request to all Muslim Ummah and internatiopnal Communities to do much and demand for early seize fire from Israel. And they have to put pressure on the Israel for immediate seize fire from one side immediately.
I think if we are fail to do so then Palestine civilian faced much Casualities and losses. And it will enhance Muslim people anxiety and anger in lang run..
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