The atmosphere
The atmosphere of earth is the layer of gases commonly known as air retained by Earth Gravity surrounding the planet Earth forming its planetary atmosphere. atmosphere of Earth protect life on earth by creating pressure allowing for liquid water to exist on the earth surface. Atmosphere consists of different layer of varying density, with the highest density near the surface of the earth. It divided into 5 layers they are:
1 troposphere
2 stratosphere
3 mesosphere
4 thermosphere
5 exosphere
- What is troposphere?
Troposphere is the lowest layer of Earth atmosphere where nearly all weather condition takes place the lowest layer of atmosphere stretches from the south of the earth to 8 km at the pole and 18 km over the equator. It contains 75% of atmosphere mass and 99% of total mass of water vapour and aerosols. The temperature decreases at the rate of 1 Degree Celsius for every 165m. Average height of troposphere is 18 km in the tropics,17km in the middle latitudes, 6 km in the polar regions in winter the total average height of troposphere is 13km. The rate of decrease in temperature with height is called Normal lapse rate. the layer contains cloud,and all the changes in weather take place in this layer - What is stratosphere?
Second lowest layer of atmosphere is stratosphere. the stratosphere is located above the troposphere and below the mesosphere.
We have stratosphere ‘strat’ means layer. This layer of our atmosphere has its own set of layers. It extends upto the height of 50 km. The stratosphere contains the ozone layer, which absorb the ultraviolet radiations of the Sun on account of clear skies and absence of convection currents,aircraft fly in this zone. Temperature increases with height in stratosphere. The zone separating the stratosphere and mesosphere is called stratopause.
Why temperature increases with height in stratosphere?
The temperature increases with height in stratosphere because the Ozone Layer absorb the greater part of the Solar ultraviolet radiation . More light is absorbed at higher altitude compared to the lower part of the stratosphere.
- What is mesosphere?
Mesosphere Greek mesos which means middle is the third layer of the atmosphere directly above the stratosphere and directly below the thermosphere. in mesosphere temperature decreases as altitude increases. Extending upto the height of 80 km temperature once again start decreasing with increase in height in this layer.the zone separating mesosphere and thermosphere is called mesopause.
Why temperature decreases with height in the mesosphere?
Within the mesosphere temperature decreases with increasing height due to decreasing absorption of solar radiation by the rarefied atmosphere and increasing cooling by CO2 radiative emission. in the mesosphere the thin air and small amount of ozone prevent the air from warming up. - What is thermosphere?
Thermosphere is a layer in the Earth atmosphere directly above the mesosphere and below the exosphere. the temperature is located between 80 and 400km. In this layer temperature increases with height the layer is known as ionosphere because it consists of electrically charged particles called ions.
Why temperature increases with height in the ionosphere ?
The temperature increases rapidly with height in this layer due to the absorption of huge amount of incoming high energy solar radiation by atoms of nitrogen and oxygen. Earth atmosphere is extremely hot compared to surface temperature. - What is exosphere?
The outermost layer of the atmosphere is known as exosphere molecules are gravitationally bound to that body. Exosphere is the uppermost layer the atmosphere thins out and mergers with interplanetary spaces.
2 AURORA
Aurorae National electrical phenomenon characterized by the appearance of reddish or green light in the sky, specially near the northern or southern magnetic poles.an aurora sometimes referred to as Polar lights, northern lights and southern lights is a natural light in the earth’s sky. These are the result of Collision between gaseous particle in the earth’s atmosphere with charged particles released from the sun atmosphere.
The aurora borealis is popularly known as northern lights, whereas its southern counterpart is known as the aurora Australia or the southern lights..
3.COMPOSITION OF ATMOSPHERE.
The Atmosphere of earth is a layer of gases, commonly known as air. Retained by earth’s gravity. The density of atmosphere is maximum at the surface and decreases with height.about 99% of the mass of atmosphere is confined up to a height of 32 km from the surface of the earth.
CARBON DIOXIDE.
Carbon dioxide allows the short wavelength and high frequency radiation but does not let the long wavelength and low frequency to pass to the atmosphere. Carbon dioxide consist of carbon atom covalently double bonded to two oxygen atoms. it occurs naturally in earth atmosphere as a trace gas. Items of a part of Terrestrial radiation and reflects back some towards the Earth surface. Increasing the temperature of the earth. The phenomenon is called greenhouse or glass house effect. CO2 is soluble in water. CO2 who is a green gas and is largely considered responsible for global warming. There is an increase in the concentration of Co2 in the atmosphere on account of human activities such as burning of fossil fuels.
WATER VAPOUR.
Water vapour or aqueous vapour is the gaseous phase of water. It is the one state of water within the Hydrosphere. Water vapour can be produced from the evaporation or boiling of liquid water or sublimation of ice. Water vapour absorb part of the isolation from
The sun and thus prevent some of the incoming isolation from reaching the surface of the earth. At the same time water vapour absorb the heat radiated from the Earth.thus, water vapour act like a blanket, preventing the Earth to become either too cold or too hot.
Water vapour in air varies with the following:
- Latitude: latitude is a Geographic co-ordinate that specified the north south position of a point on the earth surface. Latitude is an angle which ranges from zero degree and the equator to 90 degree at the poles. At lower latitude, it can reach up to 4% and at Higher latitude,it can be less than 1%.
2.altitude: it is a distance measurement,usually in the vertical or ” up” direction, between a reference datum and a point or object. At higher altitudes water, water vapour content is lower.
DUST PARTICLES
The highest concentration of dust particles is in the subtropical and temperate regions. Within the reasons, deserts have the highest concentration on account of negligible rainfall and dry winds. Concentration of dust particles is low in the equatorial reason because continuous rainfall makes dust particles to settle down on the surface of the earth. Dust in homes, offices and other human environment contains small amount of plant, human and animal hairs.
4.WEATHER AND CLIMATE.
Weather is the momentary state of the atmosphere which reflects short term conditions of atmosphere while climate refers to the average of the weather condition over a long period of time which is minimum 35 years. Weather can change from minute to minute minute, hour to hour , day to day and season to season climate is the average of weather over time and space. Important constituents of weather and climate and rainfall, temperature, atmospheric pressure, and humidity. Constituents of weather and climate. - Temperature
Daily average temperature = 24 reading of temperature on hourly basis/24
Monthly average temperature = daily average temperature for all the days of month/number of days in a month.
Annual range of temperature is = month average of the coldest month to monthly average temperature of the warmest month. - Rainfall
Rain is liquid water in the form of droplets that have condensed from atmospheric water vapour and then become heavy enough to fall under Gravity. Rainfall is measured in centimetres. Rainfall is measured using a cylindrical instrument called rain gauge. The rain gauge is
placed at a location exposed to sky. Rainfall in this vessel and after sometime the accumulated “height” of water is calculated manually automatically.
The sum total of these readings over a year is called annual rainfall. The average of these readings over a minimum period of 35 years is called annual average rainfall. - Atmospheric pressure.
Atmospheric pressure also called barometric pressure , is a pressure within the atmosphere of the earth. Atmospheric pressure can be measured with a Mercury Barometer which is commonly used synonym barometric pressure . Standard atmosphere is a unit of pressure defined as101,325 pa. Which is equivalent to 760 mm hg,29.9212 inches hg,14.696 psi.near the earth face the pressure decreases with height at a rate of about 3.5 millibars for every 30 m. At height above 1500 to 3000 m, the pressure is low enough to produce mountain sickness and severe physiological problems unless careful acclimatization is undertaken is undertaken. - Humidity
Humidity is the concentration of water vapour present in the air. The gaseous state of water is generally invisible to the human eye. Humidity indicates the The likelihood of precipitation ,dew or fog to be present . - 🔸️Absolute humidity: it is a measure of water vapour in the air, regardless of temperature. It Expressed as grams of moisture per cubic metre of air. Total amount of water vapour carried by a given amount of hot air is known as absolute humidity the water vapour carrying capacity of air changes with temperature. Hot air can carry more vapour vapours and thus higher humidity.
🔸️Relative humidity: it refers to the the water vapour content in the air as part of airs total water vapour carrying capacity. It is the ratio of partial pressure of water vapour the equilibrium vapour pressure of water at a given temperature. Relative Humidity depends on temperature and the pressure after system of interest.
🔸️Saturation: conversion of an unsaturated to a saturated chemical compound. Air is said to be saturated when its relative humidity is 100%. as hot air is light in weight.it rises up in the atmosphere. With the rise of air, the temperature of air reduces.
