Infrared Radiations

Portion of the eletromagnatic spectrum that

Amazing Antartica

Antarctica is the coldest place on earth.It's

freezing air tends to be extremely dry because

very cold air holds only a small amount of

water vapour

Beneficial Effects of UV radiation

A positive effect of UVB exposure is that it induces the production of vitamin D, in the skin. It has been estimated that tens of thousands of premature deaths occur in the United States annually from a range of cancers due to vitamin D deficiency. Another effect of vitamin D deficiency is osteomalacia (the adult equivalent of rickets), which can result in bone pain, difficulty in weight bearing and sometimes fractures. Other studies show most people get adequate Vitamin D through food and incidental exposure.
Many countries have fortified certain foods with Vitamin D to prevent deficiency. Eating fortified foods or taking a dietary supplement pill is usually preferred to UVB exposure, due to the increased risk of skin cancer from UV radiation.
Ultraviolet radiation has other medical applications, in the treatment of skin conditions such as psoriasis and vitiligo. UVA radiation can be used in conjunction with psoralens (PUVA treatment). UVB radiation is rarely used in conjunction with psoralens. In cases of psoriasis and vitiligo, UV light with wavelength of 311 nm is most effective.

Ozone Deplection

Ozone depletion describes two distinct, but related observations: a slow, steady decline of about 4 percent per decade in the total amount of ozone in Earth's stratosphere since around 1980; and a much larger, but seasonal, decrease in stratospheric ozone over Earth's polar regions during the same period. The latter phenomenon is commonly referred to as the ozone hole.
In addition to this well-known stratospheric ozone depletion, there are also tropospheric ozone depletion events, which occur near the surface in polar regions during spring.
The detailed mechanism by which the polar ozone holes form is different from that for the mid-latitude thinning, but the most important process in both trends is catalytic destruction of ozone by atomic chlorine and bromine.[1] The main source of these halogen atoms in the stratosphere is photodissociation of chlorofluorocarbon (CFC) compounds, commonly called freons, and of bromofluorocarbon compounds known as halons. These compounds are transported into the stratosphere after being emitted at the surface. Both ozone depletion mechanisms strengthened as emissions of CFCs and halons increased.
CFCs, halons and other contributory substances are commonly referred to as ozone-depleting substances (ODS). Since the ozone layer prevents most harmful UVB wavelengths (270–315 nm) of ultraviolet light (UV light) from passing through the Earth's atmosphere, observed and projected decreases in ozone have generated worldwide concern leading to adoption of the Montreal Protocol banning the production of CFCs and halons as well as related ozone depleting chemicals such as carbon tetrachloride and trichloroethane. It is suspected that a variety of biological consequences such as increases in skin cancer, damage to plants, and reduction of plankton populations in the ocean's photic zone may result from the increased UV exposure due to ozone depletion.

Global waming

The term "global warming" is a specific example of the broader termclimate change, which can also refer to global cooling. In common usage the term refers to recent warming and implies a human influence.[6] The United Nations Framework Convention on Climate Change (UNFCCC) uses the term "climate change" for human-caused change, and "climate variability" for other changes.[7] The term "anthropogenic global warming" is sometimes used when focusing on human-induced changes.
Earth's climate changes in response to external forcing, including variations in its orbit around the sun (orbital forcing),[8][9][10] volcanic eruptions, and atmospheric greenhouse gas concentrations. The detailed causes of the recent warming remain an active field of research, but the scientific consensus[11] identifies elevated levels of greenhouse gases due to human activity as the main influence. This attribution is clearest for the most recent 50 years, for which the most detailed data are available. In contrast to the scientific consensus that recent warming is mainly attributable to elevated levels of greenhouse gases, other hypotheses have been suggested to explain the observed increase in mean global temperature. One such hypothesis proposes that warming may be the result of variations in solar activity.[12][13][14][15]
None of the effects of forcing are instantaneous. The thermal inertia of the Earth's oceans and slow responses of other indirect effects mean that the Earth's current climate is not in equilibrium with the forcing imposed. Climate commitment studies indicate that even if greenhouse gases were stabilized at 2000 levels, a further warming of about 0.5 °C (0.9 °F) would still occur.[16]

RAINBOW

Series of concentric, coloured arc that may be see when light from a distant soure-usually the sun-falls on a collection of water droups such as in rain, spray or fog. The colered ray of the rain bow are caused by the refraction and total intanel raflection of light ray that enters the drop,each colour beeing bend through slightly different angle.Hence yhe different colours are spread upon emerging from the droup.The most brilliant and most common rainbow is the so-called rainbow,which results from light that emerges from the drop after one internal reflection.The colour of the arc (from outside to inside) red,orange,yellow,green,blue,indigo and violet. Occationaly a less-intese secotary bow may be observed;it has its colour sequence reversed.