Category Environtal Studies

                We know that there is no single climate across the globe. When there is monsoon in India, there is heat and drought elsewhere in the world. In the case of our planet, it has faced prolonged periods of climates, which persisted for very long time.

                Several types of climates can be found on Earth. The difference in climates depends on the distance of a particular region from the equator, altitude, moisture, wind-pattern, soil, vegetation, pollution etc. Thus, there are many forces that control and change the climate. The climates will gradually alter when these factors undergo change.

                The extended climatic changes also depend on the different ages Earth has gone through over the period. For example, Ice Age was a period of prolonged extreme cold climatic condition. It was an age marked by vast snow and ice sheets all the year round. The earth has experienced many Ice Ages. The most recent Ice Age occurred in the Pleistocene period. However, it was thousands of years ago.  

                Besides closeness of the earth to the sun, volcanic eruptions and certain other natural phenomena can also cause changes in the earth’s climate.

            There may have been times when you had to cancel a journey due to heavy rain; or your parents warned you of excessive heat and forbade you from playing outdoors. Have you ever wondered how to describe such changes, often sudden and unpredicted such as a rain, in the atmosphere? Is it a change in climate, or in weather?

            Earth is able to support a wide variety of living beings because of its diverse regional climates. These climates range from extreme cold at the poles to tropical heat at the Equator. Regional climate is often considered as the average weather in a place over more than 3 years. A region’s climate, therefore, is often described as sunny, windy, dry, or humid.

          However, these events can also describe the weather in a certain place, but while the weather can change in just a few hours, climate changes over a longer span of time.

            Earth’s global climate is an average of regional climates. The global climate has either cooled or warmed for longer periods throughout history. Nowadays, however, we are experiencing unusually rapid warming of our planet.

                      Our atmosphere is the protective covering over the earth. Although there are no perceivable layers or distinguishable boundary marks, the atmosphere can be divided into layers for the sake of comprehension. The atmosphere comprises of five layers: the troposphere, the stratosphere, the mesosphere, thermosphere and the exosphere.

                    Animals and plants live in the troposphere. This is because this layer is rich in oxygen, which is an indispensable element for the survival of life. The troposphere be-gins at the surface of the earth and extends to between 7 km at the poles and 17 km at the equator. The tropopause is the boundary between the troposphere and stratosphere.

                        The next layer is called stratosphere and it extends from the tropopause to about 51 km upwards. The stratopause, which is the boundary between the stratosphere and mesosphere, typically is at 50 to 55 km. The mesosphere extends from the stratopause to 80-85 km. It is in this layer where most meteors burn up upon entering the atmosphere.

                        The top of the thermosphere is the bottom of the exosphere, called the exobase. The height of exosphere varies with solar activity and ranges from about 250 to 800 km. The outermost layer of Earth’s atmosphere is called exosphere.

              In the biting cold of a winter morning, we would prefer to lie curled up, wrapping ourselves in the comfort of a thick blanket. If necessity compels us to get out of our home, we would wear a pullover to warm ourselves. The pullover and blanket help us keep the chill at bay. While Man has invented clothing to adapt to the change of seasons and climate, our earth has a natural blanket called atmosphere.

              Atmosphere protects our planet from harmful ultraviolet rays of the sun. It acts like a blanket around the earth. It not only protects our planet from the sun but also provides the conditions necessary for the sustenance of life on Earth. Life exists on Earth because of atmosphere.

              Dry air in the atmosphere consists of 78 per cent nitrogen, 21 per cent oxygen, 1 per cent argon and other inert gases, such as carbon dioxide. Other than these gases, there are many other gases in the atmosphere too. The ozone layer of the earth’s atmosphere plays an important role in preventing the ultraviolet (UV) radiation from reaching the planet’s surface.

            There is a variety of water bodies on earth. They differ from each other in terms of the amount of water they hold, the salinity of water and variety of ecosystems they contain.

            We call a body of water a lake when it is inland and is not part of an ocean, lakes are larger and deeper than a pond and are fed by a river, Natural lakes on Earth are generally found in mountainous area, rift zone and areas with ongoing or recent glaciations. Other lakes are found in basins, which have no connection to seas, 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. Lake Superior is the longest fresh water lake in the world. It is 560 km long with a surface area of 82,100 sq. km. On the other hand, a pond is a body of water that does not flow anywhere. Ponds are either natural or man-made, and are usually smaller than a lake. Ponds and lakes are distinguished from streams by the speed of their currents.

Picture Credit : Google

            Civilizations world over have developed on the banks of great rivers. Our nation derives its name from a river! Rivers have been not only the backbones of civilizations, but also home to many ecosystems.

          Rivers are large natural streams of water flowing into an ocean, a lake or any larger body of water. Unlike oceans, rivers, lakes and waterfalls are freshwater ecosystems. Water within a river is generally collected from precipitation through surface runoff, groundwater recharge, springs, and the release of stored water in natural ice and snow-packs such as glaciers.

            There are several other names to denote smaller rivers, such as stream, creek and brook. Most small rivers and ponds appear only in monsoons, as rain is their main source of water. Therefore, they dry up in summers. Such rivers are called non-perennial rivers. On the other hand, big rivers that contain water throughout the year are called perennial rivers.  

            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.

Picture Credit : Google