Category Social Sciences

Storm and Flood

How big are hurricanes?

Hurricanes can measure between 320 and 480 km across. They travel at speeds of 16 to 24 km/h, growing larger and stronger as they move. Usually they travel west, and then swing east as they reach cooler regions, before gradually dying out. Repeated hurricanes occur during the storm season, and there may be as many as 15 in a single year. In the USA the National Weather Service tracks hurricanes coming out of the Caribbean and the Gulf of Mexico.lt forecasts the time when they will reach land and the strength of the accompanying wind. 

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The eye of storm

What would you see inside the centre of a hurricane? If you stood in this area, called the eye of the hurricane, you would be in for a surprise. After the violent winds and torrential rain pass over, the wind suddenly drops. A wall of dark churning clouds, hundreds of metres high, surrounds you. There are light breezes and the Sun shines brightly. But you don’t have long to enjoy this peaceful sunny weather, because as the hurricane continues its destructive path it carries the eye with it. You will soon be enveloped in the storm once again. 

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How are hurricanes formed?

Hurricanes are powerful tropical storms that can cause serious damage. They form near the Equator, where warm, moist air rises, drawing in cooler air below. The air moves in a spiral, eventually forming a whirling mass. Rising warm air continues to cool and drop down in the centre of the spiral to repeat the process. The winds inside a hurricane travel at speeds up to 200 km/h. Hurricanes form in the Atlantic Ocean, passing over the West Indies and the southern United States. Similar storms in the Pacific Ocean are called typhoons, whereas in the Indian Ocean they are called cyclones. 

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Storm and Flood

Which world cities are at risk from flooding?

Many of the world’s cities are low lying and threatened by flooding. Bangkok, in Thailand, and Venice, in Italy, are typical old cities built by water because they relied on shipping. Both cities are built on mud and are gradually sinking, increasing the risk of flooding. Sea levels around the world are predicted to rise during this century, with the possibility of devastating flooding in places. Many cities in the Netherlands are below or at sea level. They are always in danger of flooding although elaborate defences help to protect them. The Thames Barrage has been built to prevent high tides flooding the city of London. 

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What are tornadoes?

Tornadoes are violent destructive whirlwinds whose force is concentrated into a much smaller area than that of a hurricane. They are very common in the central United States, where they cause enormous damage. Tornadoes travel across the land at high speed, and the roaring noise they make can be heard 40 km away. A tornado happens when huge masses of clouds moving in different directions meet. The air begins to spin in a spiral, and a funnel of twisting air reaches out towards the ground. The low pressure in the funnel sucks up soil, dust and anything else it touches — even cattle.

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Storm and Flood

What causes floods?

Flooding occurs when water cannot drain away fast enough in the rivers. In areas of non-porous rock, water runs off the land very quickly and streams and rivers soon overflow. Flooding also happens when winter snows thaw in spring. Huge floods cover parts of Siberia every spring, when snow melts while the rivers are still iced up. Low-lying coastal lands are vulnerable to flooding, especially when gales and high tides cause water to flow inland. Low-lying Bangladesh is particularly liable to this kind of flooding. In addition, melting snow in the Himalayan Mountains adds huge amounts of water to Bangladesh’s rivers, increasing the flood risk. 

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Where were the worst floods?

Some of the most terrible floods known were in China along the Hwang-he, or Yellow River. The river burst its banks in 1931, killing more than 3.5 million people. For centuries, dykes have been built to prevent flooding, but these burst when the water flow is too great. Huge dams and sluice gates have been installed to reduce the risk of flooding. 

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How did Shackleton rescue his crew from the Elephant Island?

               In the Elephant Island, Shackleton’s party divided into two. Twenty one men were asked to stay back on the island. Shackleton left the island with five chosen rowers, to find a way out and to come back and rescue the members stranded on the Elephant Island.

               Shackleton braved the Southern Ocean for 16 days. Soon, they made a landfall. Unfortunately, three members of the party were too sick and exhausted to continue. Shackleton and the two others climbed the icy mountains. At last they reached their destination on South Georgia Island. Shackleton succeeded in chartering a steamship to rescue his men.

               On 30th August 1916, Shackleton managed to return to the Elephant Island. And he rescued his men from the Elephant Island. 

What were the hardships faced by Shackleton and his expedition to Antarctica?

              Ernest Shackleton set out on the ‘Imperial Trans-Antarctic Expedition’ in 1914. The expedition faced terrible hurdles throughout the journey. Their ship ‘Endurance’ became beset in the ice of the Weddell Sea on the way. He and his crew were forced to spend the whole of the 79 days of the winter there. Finally, the crew was forced to abandon the ship, because it was about to be crushed by the ice.

               However, they had saved a large quantity of food and gear, as well as their three boats. For three months the ice floes took them further to the north. Food shortage became acute as weeks passed. They caught seals and ate their meat. So they could conserve the remaining packaged rations. The most dangerous thing was the cracking up of ice. Sometimes, huge killer whales charged up from below, and sought to attack them.

               Later, Shackleton found that instead of making good progress westwards, they had actually travelled 48 kilometres to the east, as a result of the drifting ice. However, they finally made a landfall on an uninhabited island known as the Elephant Island. 

Why was Ernest Shackleton’s voyage remarkable?

               Sir Ernest Henry Shackleton was an Irish born polar explorer who led three British expeditions to the Antarctic.

               In 1901, Shackleton joined his first expedition to the Antarctic. Unfortunately, he was sent home early due to bad health, after he, and his companions Scott and Edward Adrian Wilson set a new southern record by marching to latitude 82°S.

               In 1914, he set off on his own expedition to Antarctica. Shackleton was in a race with Roald Amundsen to reach the South Pole. The race ended in December 1911, with Roald Amundsen’s conquest.

               Shackleton later planned a voyage to the South Pole, and while returning, he wanted to pick a different route to the Ross Sea, and thus, become the first person to cross the Atlantic Ocean.

               To this end, he made preparations for what became the Imperial Trans-Antarctic Expedition. On 1st August 1914, Shackleton departed London on the ship ‘Endurance’ for his voyage to the South Pole. There were unimaginable hurdles throughout the voyage, which Shackleton overcame with his will power, and leadership quality.