Essential Knowledge Capsules Questions and Answers
When does volcano occur?
The temperature of the earth’s interior keeps on increasing. Nearly at depth of 30 km, the temperature is so high that even rocks start melting. These rocks, when melt, start expanding. These molten rocks are known as magma which finds its way through some openings found in the crust of the earth.
At some places, the crust is weak and the pressure of molten rock or ‘magma’ is very high and it even breaks the crust with its pressure and starts coming out. This is how a volcano occurs. The smoke, ashes and stone pieces, which come out of a volcano are known as lava. When these ashes cool down, it solidifies into mountains.
When does earthquake take place?
At earthquake is a sudden vibration or tremor in the earth’s crust. Due to the internal upheavals of the earth, malformation takes place. The excessive pressure between the layers of the rocks cause sudden cracks. They cause tremors or waves which move in different directions from the centre of disturbance.
Animals have the power to detect even the slightest tremors that precede the main earthquake. In the year 1906, there was a major earthquake in San Francisco in North America which killed many people and even caused damages to properties. There have been many earthquakes in the past, which have caused major devastations.
When does water vapor changes into Snow?
When the water vapor freezes in the atmosphere, it changes into snow. Snow is nothing but merely frozen water, which appears to be clear and transparent. Due to the presence of currents in the air, tiny crystals are formed, which carry them up and down. These tiny crystals fall and rise according to the movements of air currents.
When these crystals become big enough, they float down towards the ground and are known as ‘Snow Flakes’. There are red, green, blue and even black snowfalls in many parts of the world. This happens due to the presence of tiny fungi in the air that gets collected by the snow when it falls.
When does Tsunami Occur?
Tsunami is a Japanese word, ‘Tsu’ means harbor while ‘nami’ meals wave. In the earlier times, tsunami was referred to as the tidal waves. These are shallow water waves with long periods and wave lengths. It occurs when, the sea floor deforms itself abruptly. Whenever, an earthquake occurs beneath the sea, the water, where the deformation has taken place, gets displaced and waves are generated. It also happens whenever, there is a volcanic eruption. The water gets uplifted and thus tsunami occurs. It causes devastation by damaging the property and loss of lives if it occurs near the coastline.
When are Glaciers formed?
A glacier is a body of ice which flows down through valleys. It is formed when fresh and fluffy snow is squashed together to form a firm and a solid mass of snow. As this mass of snow piles up, the air is driven out and the snow granules come quite close to each other. These snow granules melt under the pressure, and again freeze to remain intact into glacier ice. Sometimes, it takes about 50 to 100 years for a glacier to form.