Category Science

Why are blizzards, dangerous?

A blizzard is a snowstorm. Strong winds blow the snow into drifts and it can be difficult to see. A blizzard can bring a busy city to a standstill. People and traffic can’t move about, and schools and offices have to be closed.

Amazing! You don’t only get snow in cold places. In 1981, snow fell in the Kalahari Desert in Africa for the first time in living memory. The temperature dropped to a chilly minus 5°C.

Which is the snowiest place?

The snowiest place in the world is Mt Rainier in Washington, USA. In one year, snow 30 metres deep fell there. That’s enough snow to build a snowman as tall as 17 people. Fancy having a go?

What is a hailstone made from?

A hailstone is a small ball of ice that starts life in a thundercloud. Inside the cloud, a chip of ice is tossed up and down many times. It gets coated in layers of ice, just like the layers of an onion.

Is it true? The biggest hailstone was the size of a peach.

No. It was bigger than that! Hailstones are usually the size of peas but the biggest was the size of a Watermelon. It fell in Kansas, USA, in 1970.

Picture Credit : Google

When do thunderstorms happen?

Thunderstorms usually happen on a hot, summer’s day when the air is warm and sticky. Watch out for huge, dark, tall thunderclouds gathering in the sky. They’re a sure sign a storm’s brewing. Time to head indoors!

What makes thunder rumble?

Lightning is incredibly hot, about five times hotter than the Sun’s surface. As it streaks through the sky, it heats the air so quickly that it makes a loud booming sound. This is the sound of thunder.

Where do thunderstorms begin?

Thunder starts in cumulonimbus clouds. They turn the sky purply black and blue. Some of these clouds are massive. The tallest can grow 18 kilometres high. That’s more than twice the height of Mt Everest.

Is it true? Lightning happens before thunder.

No. They happen at exactly the same time. But you see lightning before you hear thunder because light travels more quickly than sound.

Amazing! The Vikings believed that thunder was caused by the bad-tempered god, Thor, hurling his hammer across the sky.

Picture Credit : Google

Why do volcanoes blow their tops?

Volcanoes are mountains that spit fire. Deep under the Earth there is red-hot, runny rock called magma. Sometimes the magma bursts up through a crack in the Earth’s crust and a volcano erupts.

Amazing! Some of the world’s highest mountains are volcanoes. They include Mt Kilimanjaro in Africa. Luckily for this nosy lion, Kilimanjaro is now long extinct.

What is lava?

Once magma has erupted from a volcano, it is called lava. Some lava is thick and lumpy. Some is thin and runny. In the air, it cools and turns into hard, black rock.

Is it true? Volcanic ash can flow as fast as a train.

Yes. Clouds of gas and ash can flow across the ground at over 160 kph!

What happened to Pompeii?

In AD 79, Mt Vesuvius in Italy blew its top in a massive explosion. The nearby city of Pompeii was buried under a huge cloud of hot ash and rock. Thousands of people were suffocated. Others fled for their lives.

Picture Credit : Google

What makes the Earth shake?

The Earth’s surface is cracked into enormous pieces which drift on the red-hot, runny rock below. Sometimes two pieces push and shove each other, making the Earth shake.

How much damage do earthquakes cause?

Big earthquakes do lots of damage. Huge cracks open up in the ground. Houses, roads and bridges shake and fall down. In the worst earthquakes, many people are killed and injured by buildings that collapse on them.

How do scientists measure an earthquake?

An earthquake sends shock waves rippling through the ground. Scientists study these waves to see how big the earthquake is. They measure earthquakes on a scale of 1 to 10. Each quake on the scale is 30 times worse than the one before.

Is it true? People used to think earthquakes were caused by fish.

Yes. In Japan, people thought quakes were caused by a giant catfish wriggling about on the sea bed. The gods had to put a rock on the fish’s head to make it stay still!

Picture Credit : Google

How do floods happen?

Many floods happen when it rains very heavily and rivers overflow. They burst their banks and flood the land all around. You also get floods in stormy weather when high tides or gigantic waves sweep on to the shore.

Amazing! The Thames Barrier was finished in 1984 to stop the River Thames flooding and drowning London. Ten huge steel gates swing up to make a massive dam.

What are flash floods?

Flash floods are floods which happen very suddenly, with no warning. Sometimes there isn’t time to evacuate buildings in the flood’s path. Flash floods can happen in the desert too, during a rare downpour of rain.

Is it true? Floods can wash whole buildings away.

Yes. In 1955, a flood in the USA washed a four-storey wooden hotel clean away. Imagine how surprised the guests were when they looked out of their windows!

Are some floods useful?

Yes, they are. The River Nile in Egypt used to flood every year, leaving rich mud on the fields. The mud made the soil ideal for farmers to grow bumper crops. The Nile doesn’t flood anymore because a large dam was built to store its water.

Picture Credit : Google

From Kerala to Assam, floods cause widespread damage

The one word used repeatedly to describe several natural events across the world this year has been “unprecedented”. And it is no different for rains and subsequent floods. Be it Assam and Kerala in India, neighbours China, Bangladesh and Nepal or far away Africa and the U.S., the quantum of rain dumped so far has been unheard of, resulting in floods and landslides. And it did not help that these rains have come in the midst of the pandemic, rendering a twin blow to the people. According to new reports, monsoon rains this season have affected about 10 million people in South Asia alone, and this includes 1.3 million in Assam. In September, large areas of Africa witnessed rains with intensity not recorded earlier. In mere seven hours, Senegal recorded an amount of rain that usually takes an entire rainy season from July to September! Such a crisis causes loss of not just human lives but also of wildlife. Assam’s Kaziranga National Park lost more than a 100 wild animals, including about a dozen endangered one-horned rhinoceros in the recent floods. Rains and floods also damage or change landscapes permanently, in the process shrinking or destroying wildlife habitats and causing ecological imbalance. Experts point out that extreme weather event could be a result of human-induced climate change. This change is so swift and continuous that it does not allow for nature to heal or recover, threatening to trigger irrevocable consequences for the entire planet and all of its inhabitants.

Did you know?

This July, a few residents of Assam were greeted by an unusual visitor or two – one-horned rhinoceros (occasionally with a little one in tow) escaping Pobitora Wildlife Sanctuary, about 90% of it flooded by the swelling Brahmaputra. The sanctuary has the distinction of nurturing the highest density of rhinos in the world. But it also means these pachyderms jostle for space. And floods certainly don’t help. So the fortunate and smart among the lot moved to the fingers of the sanctuary and made themselves comfortable at the houses there – rent-free! While some residents were thrilled, some weren’t. However, no instances of human-animal conflict were reported.

 

Picture Credit : Google