Topic 9- The Greenhouse Effect Flashcards
How is the greenhouse effect related to global warming?
The overall consequences of the greenhouse effect is that more and more of the Sun’s energy is being absorbed by the Earth’s temperature - global warming
There have always been periods of global warming (followed by global cooling -ice ages) in the Earth’s history. There is a very close correlation between the amount of carbon dioxide in the atmosphere and the average global temperature. However, the level of greenhouse gases in the atmosphere has risen dramatically over the past 100 years or so, since the past few decades.
What is greenhouse effect?
1) The visible surface of sun (called the photosphere) acts like a blackbody radiator, emitting peak intensity radiation in the visible part of the electromagnetic spectrum.
2) The visible light from the sun passes through out atmosphere, in a similar way to light passing through the glass in the greenhouse. Some of the visible light is absorbed by the atmosphere, but the vast majority of it hits the surface of the Earth - like the ground inside a greenhouse. 3)Much of this visible light us reflected back into space off the surface of the oceans, but some absorbed by the land.
4) The absorbed visible light is then re-emitted by the land back up into the atmosphere, but at a much longer wavelength -as infrared radiation
5) Some of the longer wavelength infrared radiation is reflected back to Earth by the layer of carbon dioxide and other greenhouse gases like methane and water vapour in our atmosphere - like sunlight reflected by the glass in the greenhouse.
The levels of carbon dioxide in the atmosphere are rising due to human activates such as:
1) the burning of fossil fuels in power stations to produce electricity, which has increased rapidly.
2) the use of cars, vans and lorries that burn petrol and diesel as fuels has also increased.
3) the destruction of vast areas of tropical rainforest for logging and to produce agricultural land
