Category Science

What is a heat dome?

Europe recently experienced an intense heatwave resulting in record temperatures owing to the creation of a heat dome. But what is a heat dome? Come, let’s find out.

A high-pressure system hovering in the atmosphere over Europe trapped the heat in a phenomenon called “heat dome”. This weather phenomenon begins when there is a strong change in ocean temperatures.

Imagine a overhead water tank in summer. As the heat rises, the water in the tank turns warm but the moisture and steam cannot escape due to the tank lid. Similarly, a heat dome occurs when the atmosphere traps a mass of hot ocean air like a lid or cap over an area in dry summer conditions.

When this hot air attempts to escape, the high pressure in the atmosphere pushes it down. Under the dome, the air unable to escape sinks and compresses, releasing even more heat. Besides, it also blocks other weather systems from moving in. This leads to an increase in temperatures at ground level. So people, crops, and other living beings under it suffer terribly.

According to scientists, heat domes are linked to the behaviour of the jet stream, a band of strong winds high in the atmosphere that generally runs from west to east. “Normally, the jet stream has a wavelike pattern, meandering north and then south and then north again. When these meanders in the jet stream become bigger, they move slower and can become stationary. That’s when heat domes can occur.”

This dome of hot air can stretch over vast regions and last for days together, leading to extreme temperatures and the formation of a relentless heatwave. The hotter the temperature the stronger the heat dome gets.

This stagnant weather pattern usually leads to weak winds and a rise in humidity. Heat domes can badly affect us, raising the risk of heat illnesses and deaths as people would not be able to cool down properly.

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How powerful is a harpy eagle?

Harpy eagles are America’s most powerful birds of prey that live in the tropical rainforest. They are a key bio-indicator, meaning if there are good numbers of harpies in the forest, then it is certain that there is a healthy number of its prey species.

In Greek mythology, the harpy was a terrifying creature with the body of an eagle and the face of a woman. Harpies flew about in flocks and had a foul smell and sharp claws.

The aptly named harpy eagle of Central and South America has a piercing gaze and fan-like crest that give it a fearsome look. It has dark slate-grey plumage. with lighter grey feathers on its head and face. A broad bib of black separates its head and underside. Its belly and legs are a startling white.

Harpies are America’s most powerful birds of prey, though not the largest (that title is held by the Andean condor). They live in the tropical rainforest, and unlike eagles that live in the open, they prefer to hunt just beneath the canopy – this in spite of having a wingspan of around 2.5 m! The wings are shorter and broader than those of other eagles to facilitate hunting among the trees. As with most eagle species, female harpies are almost double the size of males.

These fascinating eagles are extremely dexterous fliers and at the top of the food chain wherever they live. Harpies can weave in and out of branches and pluck unlucky sloths and monkeys off like ripe fruit with their wickedly curved, razor sharp talons. The back talons are longer than those of a grizzly bears at 13 cm. Sloths and monkeys are the females’ favourite food but the males prefer the smaller opossums, fawns, snakes, iguanas, and even porcupines.

A harpy eagle can perch silently for hours and hours, waiting for a meal. It can fly almost vertically, so it can attack from below as well as drop down from above. It can turn its head upside down to get a look at its prey as it zooms in. Its keen eyes can spot something as small as two cm in size from 200 metres away.

Harpy eagles are elusive and rarely seen, though their range is very wide. They are near-threatened due to logging and agriculture. No one knows how many remain in the wild – scientists believe the number could be between 20,000 and 50,000.

Fact file

  • Harpies build huge nests measuring around 1.2 m wide and 1.5 m long, big enough for a person to lie in!
  • The birds mate for life, and once a nest is built, an eagle pair may reuse and repair the same nest for many years.
  • Harpy eagles are usually quiet but they can wail, croak, whistle, click, and mew.
  • Monkeys and sloths may weigh up to eight kg but a harpy’s talons can latch on with a pressure of over 50 kg. This is bone-crushing, and the victim dies instantly.
  • Chicks are pure white and attain adult colouring at the age of three. The harpy is Panama’s national bird.
  • The eagle is a key bio-indicator. That is, if there are good numbers of harpies in the forest, then it is certain that there is a healthy number of its prey species.

Picture Credit : Google 

On a wild python chase

Articles on animal numbers dwindling may often include hunting as one of the reasons. Over the last few centuries, several creatures – large and small, and marine and land dwelling have been pushed to the brink of extinction due to mindless hunting. But here’s a species whose killing has been actively taken up and encouraged. Why? Come, let’s find out.

Among the largest of snakes, Burmese pythons are native to Asia. However, in the 1990s, thanks to the pet trade, thousands of them found homes in the U.S. It is said that over the years, many either escaped into the wild or were released there by the pet owners themselves who found it difficult to keep the snakes. When Hurricane Andrew stuck Florida in 1992, it is believed that several snakes escaped a python-breeding facility and found refuge in Everglades, a massive wetland in southern Florida. And, today they’ve turned into an invasive species. Large as they are – growing up to 20-odd feet, they feed on large mammals such as pigs and goats. Famously, or rather infamously, way back in 2005, a python tried “to swallow an alligator and exploded in the park, leaving both the predators dead”. In the last few decades, the snakes have decimated native wildlife populations of foxes, rabbits, raccoons, opossums, deer, etc., and are irrevocably altering Everglade’s ecosystem.

Considering how vast Everglades is – about 20,000 sq km, and that there are thousands of pythons out there, the authorities are constantly looking for ways to capture the snakes or control their population. In fact, cash is rewarded to those who hunt them. Even a month-long competitive hunt has been organised in the hope that the wetlands would be rid of these non-venomous reptiles.

Though Burmese pythons continue to wreak havoc in another continent, back in their native range, the story is different. They face several threats, and their numbers are declining due to habitat loss, pet trade, and use in traditional medicine. Sadly, they are listed as Vulnerable on the IUCN Red List.

Did you know?

A few years ago, two Indians – Masi Sadaiyan and Vadivel Gopal – belonging to Tamil Nadu and from the Irula tribe known for its exceptional snake-catching skills, were flown to Everglades. Within a month, the duo had caught 27 pythons. This is an impressive number considering a month-long python hunting competition in 2016 comprising 1,000 hunters managed a haul of only 106!

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WHAT BRINGS ABOUT THE END OF AN ICE AGE?

The rotation and revolution of Earth, the amount of solar radiation and the amount of carbon dioxide in the atmosphere are all factors that contribute to a warming up of Earth, which ends an ice age. Changes in ocean currents also have a major effect on temperatures on Earth.

Over thousands of years, the amount of sunshine reaching Earth changes by quite a lot, particularly in the northern latitudes, the area near and around the North Pole. When less sunlight reaches the northern latitudes, temperatures drop and more water freezes into ice, starting an ice age. When more sunlight reaches the northern latitudes, temperatures rise, ice sheets melt, and the ice age ends.

Credit: American Museum of Natural History

Picture credit: Google

WHAT ARE THE LARGEST BODIES OF ICE IN THE WORLD?

In today’s world, the ice sheets of Antarctica and Greenland. An ice sheet is a continuous mass of ice covering more than 50,000 km2. The ice sheet in Antarctica covers 14 million km2. It is 1.6 to 6.4 km thick and holds 30 million km2 of ice. The Greenland ice sheet covers about 1.7 million km2.

The Antarctic ice sheet is the largest block of ice on Earth. It covers more than 14 million square kilometers (5.4 million square miles) and contains about 30 million cubic kilometers (7.2 million cubic miles) of water.

The Antarctic ice sheet is about 2 kilometers (1.2 miles) thick. If it melted, sea level would rise by about 60 meters (200 feet).

The Greenland ice sheet is much smaller than the Antarctic Ice sheet, only about 1.7 million square kilometers (656,000 square miles). It is still the second-largest body of ice on the planet.

The Greenland ice sheet interacts much more dynamically with the ocean than the Antarctic ice sheet. The annual snow accumulation rate is more than double that of Antarctica. Glacial melt happens across about half of the Greenland ice sheet, whereas it is much more isolated on the far western part of Antarctica. Greenland’s ice shelves break up much faster than those surrounding Antarctica.

Both the Antarctic and Greenland ice sheets have caused the land under them to sink. Eastern Antarctica is about 2.5 kilometers (1.6 miles) below sea level because of the colossal weight of the ice sheet above it.

Credit: National Geographic

Picture credit: Google

IS ANTARCTICA A DESERT?

A desert is defined by the amount of precipitation (rain, snow, mist and fog) in an area. A region that receives very little precipitation is classified as a desert. There are many types of deserts, including subtropical, coastal and polar deserts. What they all have in common is a barren, windswept landscape, which makes it difficult for plants and animals alike to gain a foothold on land. This all certainly applies to Antarctica.

The average yearly rainfall at the South Pole over the past 30 years was a tiny 10 mm (0.4 in). Most of the continent is covered by ice fields carved by the wind, and craggy mountains covered in glaciers. While Antarctica is home to wonderful forests of low-lying mosses and lichens, there are only two flowering plants that can survive the harsh conditions. And most of the animals we encounter – penguins, seals, whales and seabirds – rely on seafood for sustenance.

Credit: aurora expeditions

 

Picture Credit: Google