The Oxford English dictionary defines the word Environment as
“The natural world, as a whole or in a particular
geographical area, especially as affected by human activity”
Basically, an environment is a collection of all the animals
and plants in a specific area of land or water. Examples of environments are
wetlands, deserts, grasslands, forests, and oceans.
Physical and Biological Environments:
A physical environment is made up of elements such as the
atmosphere, climate, land, and water. The biological environment includes
animals, plants, and bacteria. Both the physical and biological environments
are connected to each other and can never be separated.
Types of Environments:
Some of the types of environments are:
Urban - Urban
environments may look different from other environments, but consist of
animals, plants, and resources.
Tropical
Rainforest - Tropical rainforests have the greatest number of animal
and plant species of any environment on Earth. Located on either side of the
equator, tropical rainforests are warm and wet. They get at least 200cm of rain
each year. These environments are very lush. The forests support so much life,
because they are always wet and receive the same amount of sunlight almost
every day. Constant conditions help many species of plants and animals develop
and survive.
Deserts - Deserts
are defined by how much rain they get. Most deserts, like the Sonoran in North
America and Sahara in Africa, are hot. They receive less than 25cm of rain each
year. The South and North Poles are also deserts but very cold.
Polar - Despite
extreme cold weather, polar environments still have plant and animal diversity.
Birds and mammals that live there are adapted to survive the polar extremes.
The southernmost polar region is called Antarctica, which
means "no bears." The northern polar region is the Arctic. The name
“Arctic” comes from the Greek word arctos, meaning “bear.” Polar bears are the
bears of the Arctic. Polar penguins live only in Antarctica. They are a type of
flightless bird.
Wetlands - Wetlands
are environments where the land and the water meet and mix. Types of wetlands
are swamps, bogs, marshes, and fens.
Each wetland type is classified by the plant species that
live in it. The world’s major wetland swamps are located in Africa, North
America, South America, and Asia. The largest wetlands in the world are the
bogs of the western Siberian lowlands in Russia. These bogs are three times the
size of the United Kingdom. Wetlands are becoming one of the most endangered
environments. Many of the animals and plants living there are also endangered.
Oceans - Oceans
are the large body of continuous salt water that cover over 70% of Earth's
surface. Earth has five oceans including the Atlantic, Pacific, Indian, Arctic,
and Southern oceans. It also has 13 seas. Both vertebrates and invertebrates
flourish in the ocean environment, including the smallest and largest animals
on Earth.
Grasslands - Grasslands
are environments where grasses are the main type of vegetation. The grass
species are usually mixed with herbs and sometimes with shrubs. Less than 10%
of the land is covered with trees. Grasslands are found on every continent
except Antarctica.
In Africa (and elsewhere) grassland dotted with trees is
called savanna. Grassland wildlife species include horses, elephants, zebras,
antelopes, buffalo and bison, hawks, and snakes.
In general, the environment divided into four spheres, the lithosphere, the hydrosphere, the atmosphere,
and the biosphere as correspondent
to rocks, water, air, and life.
The
Lithosphere:
In the Earth the lithosphere includes the crust and the
uppermost mantle, which constitute the hard and rigid outer layer of the Earth.
The lithosphere is underlain by the asthenosphere, the weaker, hotter, and
deeper part of the upper mantle. The boundary between the lithosphere and the
underlying asthenosphere is defined by a difference in response to stress: the
lithosphere remains rigid for very long periods of geologic time in which it
deforms elastically and through brittle failure, while the asthenosphere
deforms viscously and accommodates strain through plastic deformation. The
lithosphere is broken into tectonic plates. The uppermost part of the
lithosphere that chemically reacts to the atmosphere, hydrosphere and biosphere
through the soil forming process is called the pedosphere.
There are two types of lithosphere:
-Oceanic lithosphere, which is associated with Oceanic crust
and exists in the ocean basins
-Continental lithosphere, which is associated with
Continental crust
The
Hydrosphere:
A hydrosphere in physical geography describes the combined
mass of water found on, under, and over the surface of a planet.
The total mass of the Earth's hydrosphere is about 1.4 × 1018
tonnes, which is about 0.023% of the Earth's total mass. About 20 × 1012 tonnes
of this is in the Earth's atmosphere. Approximately 75% of the Earth's surface,
an area of some 361 million square kilometres, is covered by ocean. The average
salinity of the Earth's oceans is about 35 grams of salt per kilogram of sea
water (3.5%)
Oceans - An ocean
is a major body of saline water, and a component of the hydrosphere.
Approximately 71% of the Earth's surface is covered by ocean, a continuous body
of water that is customarily divided into several principal oceans and smaller
seas. More than half of this area is over 3,000 meters deep. Average oceanic
salinity is around 35 parts per thousand (ppt) (3.5%), and nearly all seawater
has a salinity in the range of 30 to 38 ppt. Though generally recognized as
several 'separate' oceans, these waters comprise one global, interconnected
body of salt water often referred to as the World Ocean or global ocean. This
concept of a global ocean as a continuous body of water with relatively free interchange
among its parts is of fundamental importance to oceanography. The major oceanic
divisions are defined in part by the continents, various archipelagos, and
other criteria: these divisions are (in descending order of size) the Pacific
Ocean, the Atlantic Ocean, the Indian Ocean, the Southern Ocean and the Arctic
Ocean.
Rivers - A river
is a natural watercourse, usually freshwater, flowing toward an ocean, a lake,
a sea or another river. In a few cases, a river simply flows into the ground or
dries up completely before reaching another body of water. Small rivers may
also be termed by several other names, including stream, creek and brook. In
the United States a river is generally classified as a watercourse more than 60
feet (18 metres) wide. The water in a river is usually in a channel, made up of
a stream bed between banks. In larger rivers there is also a wider floodplain
shaped by waters over-topping the channel. Flood plains may be very wide in
relation to the size of the river channel. Rivers are a part of the
hydrological cycle. Water within a river is generally collected from
precipitation through surface runoff, groundwater recharge, springs, and the
release of water stored in glaciers and snowpacks.
Streams - A stream
is a flowing body of water with a current, confined within a bed and stream
banks. Streams play an important corridor role in connecting fragmented
habitats and thus in conserving biodiversity. The study of streams and
waterways in general is known as surface hydrology. Types of streams include
creeks, tributaries, which do not reach an ocean and connect with another
stream or river, brooks, which are typically small streams and sometimes
sourced from a spring or seep and tidal inlets.
Lakes - A lake
is a terrain feature, a body of water that is localized to the bottom of basin.
A body of water is considered a lake when it is inland, is not part of a ocean,
is larger and deeper than a pond, and is fed by a river.
Natural lakes on Earth are generally found in mountainous
areas, rift zones, and areas with ongoing or recent glaciation. Other lakes are
found in endorheic basins or along the courses of mature rivers. In some parts
of the world, there are many lakes because of chaotic drainage patterns left
over from the last Ice Age. All lakes are temporary over geologic time scales,
as they will slowly fill in with sediments or spill out of the basin containing
them.
Ponds - A pond
is a body of standing water, either natural or man-made, that is usually
smaller than a lake. A wide variety of man-made bodies of water are classified
as ponds, including water gardens designed for aesthetic ornamentation, fish
ponds designed for commercial fish breeding, and solar ponds designed to store
thermal energy. Ponds and lakes are distinguished from streams via current
speed. While currents in streams are easily observed, ponds and lakes possess
thermally driven micro-currents and moderate wind driven currents. These
features distinguish a pond from many other aquatic terrain features, such as
stream pools and tide pools.
The
Atmosphere:
The atmosphere of Earth is a layer of gases surrounding the
planet Earth that is retained by Earth's gravity. The atmosphere protects life
on Earth by absorbing ultraviolet solar radiation, warming the surface through
heat retention (greenhouse effect), and reducing temperature extremes between
day and night (the diurnal temperature variation).
Earth's atmosphere can be divided into five main layers. From
highest to lowest, these layers are:
Exosphere - The
outermost layer of Earth's atmosphere extends from the exobase upward. It is
mainly composed of hydrogen and helium. The particles are so far apart that
they can travel hundreds of kilometers without colliding with one another.
Since the particles rarely collide, the atmosphere no longer behaves like a
fluid. These free-moving particles follow ballistic trajectories and may
migrate into and out of the magnetosphere or the solar wind.
Thermosphere - Temperature
increases with height in the thermosphere from the mesopause up to the
thermopause, then is constant with height. Unlike in the stratosphere, where
the inversion is caused by absorption of radiation by ozone, in the
thermosphere the inversion is a result of the extremely low density of
molecules. The temperature of this layer can rise to 1,500 °C (2,700 °F),
though the gas molecules are so far apart that temperature in the usual sense
is not well defined. The air is so rarefied that an individual molecule (of
oxygen, for example) travels an average of 1 kilometer between collisions with
other molecules. The International Space Station orbits in this layer, between
320 and 380 km (200 and 240 mi). Because of the relative infrequency of
molecular collisions, air above the mesopause is poorly mixed compared to air below.
While the composition from the troposphere to the mesosphere is fairly
constant, above a certain point, air is poorly mixed and becomes
compositionally stratified. The point dividing these two regions is known as
the turbopause. The region below is the homosphere, and the region above is the
heterosphere. The top of the thermosphere is the bottom of the exosphere,
called the exobase. Its height varies with solar activity and ranges from about
350–800 km.
Mesosphere - The
mesosphere extends from the stratopause to 80–85 km (50–53 mi; 260,000–280,000
ft). It is the layer where most meteors burn up upon entering the atmosphere.
Temperature decreases with height in the mesosphere. The mesopause, the
temperature minimum that marks the top of the mesosphere, is the coldest place
on Earth and has an average temperature around −85 °C (−120 °F; 190 K). At the
mesopause, temperatures may drop to −100 °C (−150 °F; 170 K).[5] Due to the
cold temperature of the mesosphere, water vapor is frozen, forming ice clouds
(or Noctilucent clouds). A type of lightning referred to as either sprites or
ELVES, form many miles above thunderclouds in the troposphere.
Stratosphere - The
stratosphere extends from the tropopause to about 51 km (32 mi; 170,000 ft).
Temperature increases with height due to increased absorption of ultraviolet
radiation by the ozone layer, which restricts turbulence and mixing. While the
temperature may be −60 °C (−76 °F; 210 K) at the tropopause, the top of the
stratosphere is much warmer, and may be near freezing. The stratopause, which
is the boundary between the stratosphere and mesosphere, typically is at 50 to
55 km (31 to 34 mi; 160,000 to 180,000 ft). The pressure here is 1/1000 sea
level.
Troposphere - The
troposphere begins at the surface and extends to between 9 km (30,000 ft) at
the poles and 17 km (56,000 ft) at the equator, with some variation due to
weather. The troposphere is mostly heated by transfer of energy from the
surface, so on average the lowest part of the troposphere is warmest and
temperature decreases with altitude. This promotes vertical mixing (hence the
origin of its name in the Greek word "τροπή", trope, meaning turn or
overturn). The troposphere contains roughly 80% of the mass of the atmosphere.
The tropopause is the boundary between the troposphere and stratosphere.
The
Biosphere:
The biosphere is the global sum of all ecosystems. It can
also be called the zone of life on Earth, a closed (apart from solar and cosmic
radiation) and self-regulating system. From the broadest biophysiological point
of view, the biosphere is the global ecological system integrating all living
beings and their relationships, including their interaction with the elements
of the lithosphere, hydrosphere and atmosphere. The biosphere is postulated to
have evolved, beginning through a process of biogenesis or biopoesis, at least
some 3.5 billion years ago.
Sources –
Wikipedia.com
Globio.org
