Nashiyat.A


 * TOPIC 5: Describe how climate can be influenced by human activities (eg. Greenhouse gasses, depletion of ozone layer)**

The Climate is changing from human activities. Everyday whether they releases or not, they are always have something to do that effects the earth and it atmosphere.

**__ Green House Gasses : __** A green house gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infared range.This process is the fundamental cause of the green house effect. The primary green house gases in the earth’s atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone.



It is not possible to state that a certain gas causes an exact percentage of the greenhouse effect. This is because some of the gases absorb and emit radiation at the same frequencies as others, so that the total greenhouse effect is not simply the sum of the influence of each gas. The higher ends of the ranges quoted are for each gas alone; the lower ends account for overlaps with the other gases.The major non-gas contributor to the Earth's greenhouse effect, clouds, also absorb and emit infrared radiation and thus have an effect on radiative properties of the greenhouse gases.

Since the beginning of the Industrial Revolution, the concentrations of most of the greenhouse gases have increased. For example, the concentration of carbon dioxide has increased by about 36% to 380 ppmv, or 100 ppmv over modern pre-industrial levels. The first 50 ppmv increase took place in about 200 years, from the start of the Industrial Revolution to around 1973; however the next 50 ppmv increase took place in about 33 years, from 1973 to 2006.

**__ Ozone Layer : __** The ozone layer is a layer in Earth's atmosphere which contains relatively high concentrations of ozone. This layer absorbs 97–99% of the Sun's high frequency ultraviolet light, which is damaging to life on Earth. is mainly located in the lower portion of the stratosphere from approximately 13 to 40 kilometres (8.1 to 25 mi) above Earth, though the thickness varies seasonally and geographically.