Environmental Chemistry. greenhouse effect, global warming,. Greenhouse effect. Describe the greenhouse effect. List the main greenhouse gases and their sources, and discuss their relative effects. Discuss the influence of increasing amounts of greenhouse gases on the atmosphere.
Describe the greenhouse effect.
List the main greenhouse gases and their sources, and discuss their relative effects.
Discuss the influence of increasing amounts of greenhouse gases on the atmosphere.
Greenhouse Analogy: Energy from the sun in the form of some ultraviolet and visible light (short wavelength) passes through the glass of the greenhouse. As the light strikes various surfaces in the greenhouse they are heated. These surfaces in turn re-radiate the heat in the form of infrared radiation (long wavelength). However, the IR radiation is blocked from escaping by the glass. IR is not able to pass through the glass, hence the greenhouse air heats up fairly dramatically.
The greenhouse gases have the same property as the glass towards the IR radiation. Think of the greenhouse gases acting as an invisible glass shield around the earth.
What can the mean global temperature anomaly be used for? This product is a global-scale climate diagnostic tool and provides a big picture overview of average global temperatures compared to a reference value.
The cyclic change is caused by the seasonal variation of the growth of vegetation from the Northern Hemisphere. Starting in May the growth of plants and trees uses carbon dioxide, so the concentration decreases a little bit. Starting in October, November the growth ceases, thus causing the carbon dioxide to increase.
Water vapour absorbs most wavelengths of the infra-red radiation emitted by the Earth's surface, trapping it as heat. At some wavelengths, however, the absorption is weak or close to zero allowing infra-red radiation to escape into space. Other greenhouse gases absorb infra-red radiation at these wavelengths and reduce the amount of heat lost into space.
Greenhouse gases are gases that:
allow visible light and UV radiation (short-wavelength/high frequency) to pass through them
but (because of the nature of their covalent bonds in their molecules) absorb the infrared radiation (longer-wavelength radiation) of the same frequency as the one the Earth converts the energy from the Sun into and
reradiates this infrared radiation back to the Earth.
their ability to absorb heat or infrared radiation in the atmospheric window or not
the number of different ranges of wavelength they absorb is caused by the molecules having different types of bonds; each type absorbs at its own frequency;
the intensity of the absorption e.g. methane has 4 C-H bonds which means it can absorb more at a certain frequency!
the abundance of the chemical
the lifespan of the chemical
Compares ability of a greenhouse gas to absorb IR to the same amount of carbon dioxide which has a factor of 1.
Example: greenhouse factor of methane is 30 which means it absorbs as much as 30 molecules of carbon dioxide or 1 molecule of methane absorbs 30 times more as 1 molecule of carbon dioxide.
Human source: electrical insulators
Greenhouse effect: 24 000