Category Environtal Studies

WHICH ARE THE MAJOR OCEANS?

An ocean is a huge, continuous body of salt water. Oceanographers identify five major oceans on the basis of geography and the continents that surround them. These are the Pacific, Atlantic, Indian, Arctic and Southern (also known as Antarctic) Oceans. They cover about one-third of Earth’s surface and contain about 97 per cent of the world’s water.

Pacific Ocean

The Pacific Ocean is the largest ocean covering more than 30% of the Earth. This is close to half of the water on Earth.

It touches the west coast border of the Americas along with east Asia and Australia.

The equator divides the Pacific Ocean into two separate parts – the North Pacific Ocean and South Pacific Ocean.

Pacific means “peaceful” in Latin. It has the deepest trenches with an average depth of 3800m.

Atlantic Ocean

The Atlantic Ocean is situated between the Americas and European/African continents. The Atlantic Ocean is the second-largest and saltiest ocean in the world.

It resembles an S-shape between the Americas, Europe, and Africa. “Atlantic” originated from the Greek god “Atlas” who carried the sky for eternity.

The ocean bottom is composed of mid-Atlantic Ridge. This submarine mountain range extends all the way from Iceland to 58 degrees South latitude. It’s part of the longest mountain range in the world.

Indian Ocean

The Indian Ocean is the third largest ocean surrounding a densely populated region. It contains an additional 20% of the water on Earth’s surface.

It borders India in the North, East Africa, Australia, and the Southern Ocean. Because of the higher water temperature, it has limited marine life.

Since about 800 A.D. the Indian Ocean has played an important role in trading. For centuries, navigators have sailed along major ocean currents for shipment routes.

It is bounded by 4 tectonics plate boundaries and may include an additional plate boundary. It is the geologically youngest of the 5 oceans with spreading ridges at divergent plate boundaries.

Southern Ocean

In 2000, the Southern Ocean is the newest ocean recognized by the International Hydrographic Organization. It borders Antarctica in its entirety.

In terms of size, it’s the fourth-largest at 20,327,000 square kilometers. It extends out to 60 degrees South latitude.

It’s an extreme environment and is the least understood of the 5 oceans. This is because it is unexplored, far from populated areas, and has a severe climate.

Despite the Southern Ocean being unexplored, about 80% of all oceans in the world are unexplored. There’s still a lot of work to do for ocean exploration.

Arctic Ocean

The Arctic Ocean is the world’s smallest and shallowest ocean of all 5 oceans. Further to this, it is the coldest and least salty ocean.

In size, the Arctic Ocean is about the size of Russia. Because it’s located at the North Pole, the Arctic Ocean has polar ice. But over the years, glaciers have melted threatening sea levels to rise.

Despite the IHO recognizing it as the “Arctic Ocean”, some oceanographers still call it the “Arctic Sea”.

The Arctic Ocean is the most diverse in terms of fish species. It has a wide variety of marine species including whales, jellyfish, etc.

But because of its frigid temperatures, it has little plant life. This makes it one of the most fragile ecosystems on the planet.

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OCEANS AND SEAS ARE DIFFERENT?

The difference lies in their depth, area and variety of marine life. An ocean is deeper and covers a greater area as compared to the sea. On the other hand, a sea has more diverse plant and animal life. There are fewer plants in an ocean as there are large areas where sunlight does not penetrate. The deep-sea creatures found in the darkness of oceans are unique.

 

                          Sea

Ocean

Sea is also made up of salty water but is smaller in size compared to oceans.

Ocean covers approximately 70% of the earth’s total surface. Ocean is made up of salty water.

The largest sea is the Meditteranean Sea. The area of Meditteranean sea is approximately 1.14 million square miles.

The largest Ocean is the Pacific Ocean with an area of approximately 60 million square miles. The smallest Ocean is the Arctic Ocean covering an area of 5.4 million square miles.

Seas are usually located close to land.

Oceans are not necessarily located close to land.

Aquatic life exists in abundance in seas as seas are usually located close to the Land.

Oceans have reduced aquatic life as it is far away from the land and deeper than the Seas.

There is a large quantity of marine life in the Seas as sunlight is able to penetrate deeper into the seas, allowing photosynthesis.

The marine life in oceans is usually confined to bacteria, shrimp, microscopic planktons. This is due to lack of penetration of sunlight deep into oceans thus not giving much scope for photosynthesis.

Some of the major seas are Mediterranean Sea, Carribean Sea, South China Sea, Black Sea etc. The deepest sea is Carribean Sea with an approximate depth of 6900 metres.

The Deepest Ocean is Pacific Ocean which is around 10,000 metres deep and the Arctic Ocean is around 5600 metres deep.

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Why is Roopkund called Skeleton Lake?

During World War II. an Indian forest Ranger called Hari Kishan Madhwa made a morbid discovery in a remote glacier lake in the Himalayas in Uttarakhand. Something strange was visible in its clear water. On closer inspection, it was revealed that the lake was full of human skeletons. It came to be known as Roop Kund or Skeleton Lake. A DNA sample of 38 skeletons showed that they came from three genetically distinct groups. Who were these people? When did they die? How did they die? Where did they come from?

One old theory associates the remains to an Indian king, his wife and their attendants, all of whom perished in a blizzard some 870 years ago.

Another suggests that some of the remains are of Indian soldiers who tried to invade Tibet in 1841, and were beaten back. More than 70 of them were then forced to find their way home over the Himalayas and died on the way.

Yet another assumes that this could have been a “cemetery” where victims of an epidemic were buried. In villages in the area, there’s a popular folk song that talks about how Goddess Nanda Devi created a hail storm “as hard as iron” which killed people winding their way past the lake. India’s second-highest mountain, Nanda Devi, is revered as a goddess.

Earlier studies of skeletons have found that most of the people who died were tall – “more than average stature”. Most of them were middle-aged adults, aged between 35 and 40. There were no babies or children. Some of them were elderly women. All were of reasonably good health.

Also, it was generally assumed that the skeletons were of a single group of people who died all at once in a single catastrophic incident during the 9th Century.

Scientists genetically analysed and carbon-dated the remains of 38 bodies, including 15 women, found at the lake – some of them date back to around 1,200 years. They found that the dead were both genetically diverse and their deaths were separated in time by as much as 1,000 years.

But more interestingly, the genetics study found the dead comprised a diverse people: one group of people had genetics similar to present-day people who live in South Asia, while the other “closely related” to people living in present-day Europe, particularly those living in the Greek island of Crete. Also, the people who came from South Asia “do not appear to come from the same population”.

Genetic studies found no evidence of the presence of any ancient bacterial pathogen that could provide disease as an explanation for the cause of deaths.

Credit : BBC 

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How long does glass take to decompose?

A glass bottle takes one million years to decompose, according to the Environmental Protection Agency of the U.S. If that’s the case, why are we more concerned about plastic, which takes only about 450 years to decompose? Because, plastic can leach harmful chemicals into the soil, unlike glass. It does not mean glass is harmless-for example, tiny shards can injure creatures. But the fact is that glass can be recycled while plastic, especially single-use ones, end up in landfills, resulting in pollutions of various kinds.

When a dropped glass shatters or a rock chips the car’s windshield, it’s tempting to think of glass as a fragile material. Actually, it’s one of the longest-lasting man-made materials. The New Hampshire Department of Environmental Services estimates that it takes 1 million years for a glass bottle to decompose in the environment, with conditions in a landfill even more protected. Glass artifacts from glassmaking’s beginnings in Egypt, around 2000 B.C., still exist.

The glass-making process has been perfected over thousands of years. Glass used to be available only to pharaohs and royals but has become an everyday item. Glass can be made in several different ways, with different chemical compositions. Throughout history, however, soda-lime glass has been the most common form of glass produced, according to scientists with Texas A&M University’s Nautical Archaeology program. Most glass consists primarily of silica, a component of sand, mixed at very high temperatures with sodium carbonate or potassium carbonate and a small amount of lime for stability. Glass made with sodium carbonate (soda glass) is usually more transparent than glass made with potassium carbonate (potash glass).

Glass does break, but it does not readily break down. The glass decomposition rate is essentially nil. Over time, the surface of some glass bottles will absorb moisture. This results in devitrification, a process that causes the outer layer of glass bottles to crystallize and flake off. Devitrification takes place very slowly and results in a cloudy or iridescent appearance. Modern glass is made from an incredibly stable formula, however, so the glass bottles people throw in the garbage today will most likely remain in landfills for thousands of years, experiencing only slight devitrification.

Credit : Sciencing 

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Why have beach sands different colors?

Sand is basically the small particles of eroded larger rocks. The erosion is caused by several factors, including water and wind. Depending on the geography, the composition and colours of the sand vary. For instance, beach sand could be lighter because of calcium carbonate desposits from shells and skeletons of marine creatures. Meanwhile, desert sand comprises fine, light-weight particles that have been brought in by wind. River sand is likely to be coarse, containing even bright-coloured stones.

On some beaches, sand grain size composition varies with distance from the water. A greater proportion of finer, smaller sand grains may be pushed higher up the beach by waves or by wind, whereas larger, coarser grains are deposited closer to the water. However, beaches are complex and highly variable environments, and there are many areas where this distribution is not found because there are many conditions that affect sand size and distribution. Additional factors influencing sand grain size include the nearshore and offshore seafloor features, substrate type, sand source, currents, wind exposure, and coastline shape.

Beach sand can appear fairly uniform, but it is actually a complex mixture of substances with various dimensions. When scientists study sand, some qualities are particularly useful in characterizing the type of sand. These qualities include the colors, texture, and size of the sand grains and their material origins. In general, sand observations can be divided into three broad categories:

observations about size,

observations about shape, and

observations about the probable source of the sand.

 From these three characteristics scientists can learn about the physical, chemical, and biological processes at the beach from which the sand came.

The Wentworth scale is one system used to classify sediments, including sand, by grain size. The word sediment is a general term for mineral particles, for example individual sand grains, which have been created by the weathering of rocks and soil and transported by natural processes, like water and wind. In decreasing order of size, sediments include boulders, gravel, sand, and silt.

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How many watts is a lightning strike?

Lightning is a natural electrical discharge created by imbalances between a cumulonimbus cloud and the ground or within itself. Lightning is pure electricity involving small particles with positive and negative charges that pull toward each other like the north and south ends of magnets. Lightnings are scary and of course dangerous, but it is a subject of fascination for scientists. During thunderstorms, scientists  witness a lot of lightning.  On an average, scientists have mapped, there are about 100 lightnings per second worldwide.That’s a whopping number. Imagine the amount of energy that’s shooting up from the clouds. Each bolt can contain up to one billion volts of electricity. This means a single lightning flash has enough energy to light a 100-watt bulb for three months!  So, How many homes could a lightning bolt power? Every lightning bolt on Earth in one year, captured perfectly with no loss of energy, would contain about 4*10^17 joules of energy. Thus, all the lightning in the entire world could only power 8% of US households. Human body can tolerate a maximum of between 20,000 and 50,000 volts, which might prove to be lethal. In most cases, a person’s heart will stop after being struck by lightning, so the key to survival is having someone nearby who can administer CPR. Even if you survive, a lightning strike will have long-lasting effects on your body, including memory issues, muscle soreness and changes in mood.

People often confuse lightning with thunder. To put it simply, lightning is electricity; thunder is sound. In other words, lightning is the sudden flash of light spotted in the sky, while thunder is the roaring, cracking sound that is commonly heard during thunderstorms. And because light travels faster than sound, lightning is seen before thunder can be heard.

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