Category Science

Water evaporates when the sun shines on oceans, seas, or wet grounds or when wind blows over them. The water vapour rises up and gets converted again into tiny droplets on reaching the cold heights of the sky.

These tiny droplets form clouds which are carried here and there by the wind. If they rise further, such as on a high mountain crest, they become colder and turn into large raindrops, small ice crystals, and hailstones. These are heavy and fall to the ground as rain, and water seeps into the ground. This water returns to the sea as ground water, rivers, and streams. This cyclical process is known as the ‘water cycle’. 

The reason for this is that light travels faster than sound. The speed of light is 300,000 km per second. On the contrary, sound is slow and covers only about 330 m in one second, i.e., one kilometre in three seconds. If we count the seconds till we hear the thunder after seeing the flash of lighting in the sky and divide this value by three, we will know how many kilometres the storm is away from us. 

When we talk about cyclones, we do not usually mean the small destructive tornadoes, but instead the large tropical storms, which the coastal inhabitants face. In America, these are known as ‘hurricanes’, in East Asia ‘typhoons’, and in India ‘cyclones’. Hurricanes occur in early spring in the warm waters around Africa. During this season, copious amounts of water evaporate rise upwards, and forms clouds. This sharply reduces the pressure directly above the sea, allowing more moist air to flow in from the surrounding areas. Due to the rotation of the Earth, bundles of cloud start rotating and an air vortex is created. This vortex moves fast over the sea and wrecks widespread havoc on reaching the land. 

The weather is predicted by meteorologists—scientists who monitor weather conditions. They study the factors that lead to weather phenomena in different parts of the world. They observe and record atmospheric temperature, humidity, pressure, and precipitation and the direction and strength of winds. Weather balloons and weather stations give out information regarding the state of the atmosphere. On the basis of their findings, they make forecasts about future weather conditions. 

Universe, cosmos, and space mean the same – the space all around us and what it contains as far as we can see and think. We do not know whether the space is endless or is finite. If there were a border, what would be behind it? The astronomers are still dealing with the question of the origin of the universe and its end. An important factor to support the Big Bang theory of the origin of the universe is the ‘cosmic background radiation’, which was discovered in 1964. We still wonder whether there are intelligent civilizations somewhere in space – and are looking for them.

Unlike climate, weather depends on the seasons and can also change anytime. Meteorologists predict in the evening how the weather will be the next day. The weather is driven by the sun, which heats up the ground and the water surfaces. Evaporated water creates clouds from which thunderstorms build up, and the ensuing bursts of thunder and lightning make us flinch. Every time a cyclone hits the tropical regions, lashing rain sends people running for cover.