Why Does The Sky Appear Blue?

            A blanket of air called atmosphere, surrounds our earth. It is mainly composed of nitrogen, oxygen, carbon dioxide, dust particles, water vapors and other gases. The light coming to us from the sun has to travel through this atmosphere.

The Sky

            We all know that the sun is the main source of light for earth. When the sunlight passes through the atmosphere, it is scattered by the dust particles, water vapor and air molecules in all the directions. This is the reason why light is all around after the sunrise.

            Do you know that the sunlight is composed of seven colors- violet, indigo, blue, green, yellow, orange and red? When the sunrays pass through the atmospheric molecules, the violet, indigo and blue colors get scattered most and the red color least of them. Therefore, when we look at the sky, the light that enters our eyes mainly consists of violet, indigo and blue colors. The mixture of these three colors is almost blue. That is why the sky appears blue.

            If the earth had no atmosphere, the sky would have just appeared dark. This fact is clear when we look at the sky from the surface of the moon. It appears dark since there is no atmosphere in the moon. Similarly, the sky appears dark when we look form a spacecraft, because there are no light scattering particles in the higher space.

How do Plants Protect Themselves from Frost?

            There are over 350,000 kinds of plants in the world. All these continue to struggle to survive against storm, rain, sun and snow. These are some which die due to severe cold in winters, although before dying their seeds are dispersed on the ground, so that in autumn, they can produce new plants. However, there are some plants, which are able to protect themselves against winter.

            A coating of ice crystals is called frost. The plats are able to protect themselves against winter frost by a special method. They spared their leaves and flatten themselves against the ground. The warmth in the soil enters their leaves and the plant is protected. Some plants like myrtle and heather allow their upper parts to die but heir stem remains alive. Stems act as storage organs, both above and below the ground. They produce buds and thus preserve their species. Many plants hide themselves under the soil to escape the cold; these include tubers, bulbs and roots, which store their food according to their need. In summers, they push out green leaves and new buds.

            Some times, artificial methods are used to protect plants form frost, e.g., oil heater called smudge pots is use din the region where citrus fruits are grown. In some places, large fans are used to circulate the air, so that frost is not able to get deposited on the trees.