Structure of the Environment

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