Hi and welcome back to the channel! Today I am
covering the topic of Hydrosphere and in this video, we will look into lakes. A hydrosphere
comprises of all the forms of water found on a planet. It can be in the form of liquid,
water vapor or ice. There are around 1.4 billion cubic km of water on earth including lakes,
rivers, seas, oceans, groundwater, and glaciers. About 71 percent of the earth’s total surface
area is covered with water. The estimated mass of Earth’s hydrosphere is about 14,000,000,000,000,000,000
tonnes out of which 20,000,000,000,000 tonnes is in the form of water vapor. We can see
water vapor in the form of clouds and fog. Out of total water, 96.5 percent lies in the
ocean which is salty and undrinkable. On average ocean contains 35 gm of salt per
kg of water. A large amount of fresh water is frozen and only 0.3% is easily accessible
through lakes, rivers, etc. The frozen part of the hydrosphere is called the cryosphere.
It consists of ice caps, icebergs, and glaciers. A lake is a body of water that is surrounded
by land and is larger than a pond. The great lakes of North America are the largest fresh
water lakes in the area and second largest in volume. It comprises of Lakes Superior,
Lake Michigan, Lake Huron, Lake Erie, and Lake Ontario. The deepest and oldest lake
is Lake Baikal in Russia which is 1.6 km deep and is 25 million years old. It is created
due to the movement of tectonic plates which created a fault.
Water fills up the fault giving birth to the Lake and it contains as much water as all
the great lakes combined. Lake Titicaca is the highest lake which is
3,812 meters above sea level. It is located in the Andes mountains on the border of Bolivia
and Peru. It is the largest lake in South America by volume and area both.
The lowest lake is more than 400 meters below sea level called the Dead Sea. Although it
is called sea it is actually a hypersaline lake with a salinity of 34.2%, which means
1 kg of water contains 342 gm of salt, which makes it 10 times saltier than oceans. It
is called the Dead Sea because plants and animals can’t survive in the water due to
the high concentration of salt. Because of the high density of water, you can easily
float here. The lake is bordered by Jordan and Israel
and its main tributary river is the Jordan River.
Lakes can be open or closed. In closed lakes water leave the lake only by evaporation which
makes the water saltier. On the other hand, if water leaves the lake through rivers or
other outlets, it is called an open lake. The great salt lake in the U.S. state of Utah
is the largest saltwater lake in North America. Lakes are classified into several types such
as tectonic lakes, volcanic lakes, glacial lakes, oxbow lakes, meteorite lakes, etc.
Tectonic lakes formed due to the movement of the earth’s crust. The Caspian Sea, Sea
of Aral, Lake Baikal are some examples of Tectonic Lakes. The Caspian Sea was once a
part of Tethys Ocean which flows between the ancient continents of Gondwana and Laurasia
in the Mesozoic Era. The Caspian Sea became landlocked about 5.5 million years ago due
to the movement of the tectonic plates. Volcanic lakes are created due to the explosion
of volcanoes. When a major eruption occurs a crater originates on the top. As time passes
the crater gradually sinks and forms a caldera. Rainwater fills the caldera of a dormant or
extinct volcano creating a lake. Krakatoa Lake in Indonesia is an example of a volcanic
lake. Glacial Lake forms when a glacier erodes the
land creating a depression. The hollow space created due to erosion is also known as a
Cirque. When the glacier melts it fills the space forming a lake. The Great Lakes of North
America are the largest glacial lakes in the world.
An oxbow lake forms when a river creates a meander. Due to erosion, the meander of a
river becomes very curvy. When the river cuts through, the path of the river change which
creates a U shape free-standing body of water known as an oxbow lake. The name derives from
the bow pin of an oxbow due to its curved shape.
Solution lakes are formed when running water creates a depression in the ground by dissolving
rocks made up of sodium chloride and calcium carbonate. The solution creates cavities by
precipitation and percolating water, which further collapse to form a sinkhole. These
lakes are common in the karst regions of Croatia and Florida.
Meteorite lakes are lakes created by deadly impacts by either meteorites or asteroids.
Lonar crater lake in India is an example of a Meteorite lake created by a meteor impact
during the Pleistocene Period. It’s a saline soda lake having a high content of sodium
salts. There are also other types of lakes such as
Shoreline lakes, Anthropogenic lakes, Aeolian lakes, Organic Lakes, Landslide Lakes and
more. I guess this much information is enough for
today. The next part of this series “Hydrosphere” will be about rivers. I hope you find this
video useful. Don’t forget to like, share, comment and subscribe. Thanks for watching!