Cyclones, Glaciers and Arctic Regions
A cyclone is a storm with strong spiraling winds rotating around a moving centre of low atmospheric pressure. The centre of the cyclone is known as its eye. The movement of cyclonic hemisphere and clockwise in the southern hemisphere.
As the cold air mass and warm air mass come into contact with the cyclonic winds. It results in heavy rains and snowfall. Such cyclones are called Frontal cyclones.
Tropical cyclones occur in warm water regions of the oceans near the equator. Theses are known by different names. Over the Atlantic Ocean they are known as hurricanes but called typhoons. Hurricanes and typhoons cause havoc to ships and coastal settlements killing people and destroying properties.
A tornado is a small but violent cyclone that develops in a large thunderstorm lasting for a short time. It has dark funnel shaped cloud. Along its track trees are uprooted and building destroyed. The dust and debris pulled by the tornado from one place are heaped other some other place. During a tornado the velocity of the wind goes up to 200 kemps per hour.
On the 13-14th November, 1970. Bangladesh faced the most devastating cyclone which took away more than 10 lakh lives. Every years lakes of people die due cyclones storms and tornadoes across the globe.
A glacier is a huge mass of snow and ice which moves slowly down a valley. Glaciers generally occur in polar region and on high mountains. The speed of their movement is slow on mountain slopes. Glaciers differ in their size and velocity of movement. Usually they move about half a meter or one meter a day. But In Greenland they may move up to 15 m a day due to their heavier loads. Glaciers cover about 10% of the earths land surface. Glacier is generally found on the mountain peaks and mountain passes.
In the coastal regions of Greenland and Antarctica large masses of ices broken off from the glaciers float on the sea. They are called iceberg. Normally about one tenth part of an iceberg is above the sea level part of an under the water. Some icebergs are up to 90 meters above the sea level while 810 meters hidden under the sea were. Icebergs are of enormous size weighing up to 200 million tons.
The largest glacier in the world is Lambert about 515 km long and 70 km wide. It lies in the Australian Antarctica region. Other famous Switzerland loam in Norway ovation in France and Nishkanevelly in America.
The Arctic Ocean lies on the northern border f the earth. In its centre is situated the North Pole. Surrounded b land masses on all sides, it is completely frozen. On three sides it is flanked by northern boundaries of Asia, Europe and North America, while Greenland and other small islands exist on its fourth side. It is covered with snow all the year round and icebergs float on open seas.
Hardly any vegetation exists there because it is covered with snow. Very few people live there- the Eskimos in the northern America and green land, and the Lapps in Europe. They have learnt way to survive in this cold region. They build dome shaped snow houses called igloos by stacking slabs of snow. They live now hunting and fishing. Reindeers, seals, walrus and arctic bears are also found there. They use sledges that move very quickly on the snow.