Air is an invisible mixture of gases made up of a mass of millions of tiny gas molecules that moves randomlyandathigh speed. Without airthe earth would belifeless.
Composition of the Atmosphere
The atmosphere consists of a mixture of gases which are present in varying proportions. Its major constituents are nitrogen 78% and oxygen 21%. The rest of the gases 1% include carbon dioxide, helium, ozone, argon and hydrogen. Impurities like dust, smoke, salts, carbon monoxide and other chemicals are also present in the atmosphere. In its lower layer the atmosphere contains water vapour too. Nitrogen is the largest component and is essential for survivaland growthof plants. Oxygen is the second most plentiful gas. All living beings breathe in oxygen while the green plants breathe out oxygen. Green plants use carbon dioxide present in the atmosphere to make their food. Thus, the plants help in maintaining a balance between oxygen and carbon dioxide percentage in the atmosphere through the Process of Photosynthesis. If the plant cover is reduced, it will affect the balance between oxygen and carbon dioxide levels in the atmosphere.
Weather and climate
Weather can be defined as the sum total of the current atmospheric conditions like temperature, humidity, wind and rainfall at any given place. All of these atmospheric conditions are collectively known as the weather. Therefore, weather can be sunny, windy, rainy, cloudy or snowy. Climate in your place on the globe controls the weather where you live. Climate is the average weather pattern in a place over many years,. So, the climate of Antarctica is more quite differentthan the climate of a tropical island. So summer days are quite typical of climates in many regions of the world, even without the effects of global warming. Ifit's raining ona particular day then we are talking about the weather but if it's raining over a season for several years then we are talking of the climate. Weather can change from hour to hour or day to day and season to season. Climate can change over years. Weather and climate greatly affect the socio-economicand culturallife of the people.
WEATHER
> It can be changed many times in a day.
> Weather relates to the daily atmospheric changes and conditions.
> Weather changes occur over a small "uoias
CLIMATE
> It remains constant for a long period.
>It represents atmospheric conditions over a longer period of time (about 35 years of time period)
> Climate changes relate to a larger area.
Temperature
Temperature refers to the degrees of hotness or coldness of the air. The main source of this neat is the insolation or the amount of solar energy received by the earth. The amount of neat depends upon the latitudinal location of any place. It is higher in places near the equator and decreases pole-wards. The amount of insolation received differs from season to season and also between day and night. The earth been broadly divided into three heat zones depending upon the amount of insolation received. The temperature of any place also depends upon its height apove sea level and its distance from the sea. Places> located near the sea will experience moderate temperature but those, away from the sea, willgenerally experience extreme temperature. Of course, the temperature recordings are never solely dependent on any one factor. Various factors affect the climate of a place. Winds, ocean current, slope of land, vegetation cover are the many factors that influence the temperature recordings. A thermometer is used to measure the atmospherictemperature on a Fahrenheit ora Celsiusscale.
Air or atmspheric pressure
Many of the forces within our atmosphere are easily recognized by us like the temperature outside simply bystepping outside. We immediatelyget to knowwhetheritis cold, warm, or hot. Likewise, we can feel the amount of wind or see the level of windiness by looking at how forcefully the trees are swaying back and forth. But we cannot feel or see the atmospheric (Air) pressure. Atmospheric pressure is the amount of force or pressure exerted by the atmosphere on the objects located within it. It happens because the air presses us from all directions and our body t0o exerts a counter pressure. Scientists (meteorologists) use a specialinstrument called a barometerto measure the pressure of the atmosphere.
Ground Water
Almost 30 per cent of the world's freshwater reserves are found under the ground. When it rains, some of the water soaks into the soil passing between soil gravels and rocks and gets deposited below the earth's surface. This water is called ground water. This can take days, years, decades or millennia. Watersheds, aquifers, wellsandsprings aretheexamples ofunderground water.
Distribution of Water Bodies
Water is found in solid, liquid and gaseous forms. About 2/3rd of the earth is covered with water yet the water which is suitable for human consumption is only 3%.97% is saline water and is found in oceans and seas. This water is not suitable for human consumption. Out of the 3% of fresh water 2% is in the form of ice caps and glaciers and only 1% is available in the form of surface water. This is found in rivers, lakes, ground water or in the gaseous form as watervapour in theatmosphere. Fresh water is themost valuable natural resourceand must be usedjudiciously.
Water cycle
Water continually changes its form. The heat of the sun evaporates water which changes its form and becomes water vapour. This cools down and condenses to form clouds. This causes rain and the water returns to the earth falling on land or sea etc. Water that falls on land, collects in rivers which carry it back to the oceans. This never-ending movement water is called the water-cycle or the hydrological cycle. The amount of water available varies from place to place and from season to season. But the general pattern is almost the same. However, there are certain human activities which affect the water cycle. Cutting down of trees, polluting water bodies and wasting water can affect the water cycle. Man must make efforts to conserve this precious resource.
Waves
The surface of the earth's oceans is in constant motion, moving up and down in the form of waves. If you have been to a beach, you have witnessed waves first hand. Waves form as energy is transferred from molecule to molecule move very little. It is only the energy that actually moves. However, as waves break across a shore or crash in violent storms, they can be the sources for great mixing of an ocean's water. Everything from earthquakes to ship wrecks, creates waves; however, the most common cause is wind. As wind passes over the water surface, friction forces it to ripple. The rise and fall of water takes place in a wave. The rise is called the crest and the fall is known as the trough. The horizontal distance from one crest to another or from one trough to another is known as the wave length. The vertical distance from crest to trough is known as the wave height. Wavelength is the horizontal distance, either between the crests or troughs of two consecutive waves. Wave height is a vertical trough. Wave period measures the size of the wave in time. A wave period can be measured by picking a stationary point and counting the seconds it takes for two consecutive crests or troughs to passit. tance between a wave's crest and the next In deep water, a wave is a forward motion of energy, not water. In fact, the water does not even move forward with a wave. If we followed a single drop of water during a passing wave, we would see it moves inavertical circle, returning to a point nearitsoriginal position at thewave's end. These vertical circles are more obvious at the surface. As depth increases, their effects slowly decrease until completely disappearingabout halfawavelengthbelow thesurface.
The earth is a watery planet. 71% of its surface is covered with water which is found in oceans, seas, rivers, lakes, etc.
The hydrological cycle describes the movement of water on, in and above the earth's surface.
Waves form as energy is transferred from molecule to molecule across the surface.
Ocean water are never still. Waves, tides and currents are its main movement.
The two types of sources of water are surface water and groundwater.
Horizontal Movement of ocean water in the form of streams in a definite direction is called ocean current.
Synthetic fibre
Synthetic fibres are the result of extensive research by the scientist to improve upon naturally occurring animals and plant fibres. In general synthetic fibres are created by forcing usually through extrusion, fibre forming materials through holes into the air, forming a thread. Synthetic fibres are made from synthesized polymers small molecules. The compounds that are used to make these fibres come from raw material as petroleum based chemicals or petrochemicals. Rayon, nylon, polyester and arcylic are some synthetic fibres.
Corrosion of metals
Corrosion is used to describe that process, by which the materials, such as metals are slowly eaten away when exposed to air and moisture, When iron is left exposed to moist air, it develops, a reddish-brown, layer of rust. Rust is iron oxide, and its formation means that a part of solid iron metal has changed into a new powdery substance Fe, O,. In other words, corrosion is the wearing away of metals due to chemical reactions. Some metals, such as gold and platinum do not corrode in air. That is why gold ornaments do not lose their shine even after several years.
Petroleum refining:
The crude oil obtained from a well is a dark, viscous oil, liquid, made up of a mixture of hydrocarbons. It consists of those chemical engineering processes and other facilities used in petroleum refineries to transform crude oil into useful products such as liquefied petroleum gas (LPG), gasoline or petrol, kerosene, jet fuel, diesel oil and fuel oils. Fractional distillation is a method of separating a mixture of substances with different boiling points to obtain a number of components with similar boiling poínts. These components are called fractions. The process of separating the fractions by fractional distillation is known as refining. Crude oil is first heated to about 400°C in a furnace. The vapours formed are passed into a tall fractionating tower. The hydrocarbons with the highest boiling points condense first. They get collected near the base of the fractionating tower. As the vapour rises, the hydrocarbons with lower boiling points condense at different heights. They get separated in the fractionating tower to form different fractions.
Natural Gas
Natural gas is a naturally occuring gas mixture consisting primarily of methane, typically with 0- 20% higher hydrocarbons. It is found associated with other hydrocarbon fuel, in a coal bed, as methane rates. Natural gas įsused as a starting material for the manufacture of a number of chemicals and fertilizers.Compressed natural gas is a good source of non polluting fill for vehicles. Conservation of fuel As we know fossil fuels are non-renewable sources of energy and they took millions of years to deposit, so we must consume these sources in efficient way, so that not only we but also future generations to come will enjoy these resources. Also because if we stretched the period of exhaustion of these sources of energy, scientist will be able to find some alternative sources of energy. Also because over use of these fossil fuels will be dangerous to our environment in terms of pollution. Various steps can be taken to conserve and avoid wastage of energy in any form: When not in use, switch off lights, fans etc.
