CLIMATOLOGY-
It is the study of the myriad factors that influence weather and the influence of weather on the Environment.
It considers the past and can help predict future climate change.
ATMOSPHERE-
It is a thick gaseous envelope that surrounds the Earth from all sides and is attached to the Earth's surface by Gravitational force.
***It also serves as a shield blocking out much of the sun's Ultraviolet radiations as well as protecting us from showers of meteors.
***It contains life-giving gases like Oxygen for creatures and carbon dioxide for plants.
***The Atmosphere allows the short wave insolation to pass through it but becomes opaque for the outgoing longwave radiation.
***It acts as a huge greenhouse and maintains an average 15-degree Celsius temperature on the Earth's surface.
STRUCTURE OF ATMOSPHERE-
The atmosphere of Earth has different layers varying from one another with Density and Temperature.
**Density is highest near the surface of the Earth and decreases with increasing altitude.
**Temperature is habitable around 15-degree celsius in the lower atmosphere contagious to the surface and very high temperature at the upper atmosphere near outer space.
On the basis of Thermal conditions, the Atmosphere can be divided into 6 different layers:
(i) TROPOSPHERE-
**Troposphere is the lowermost layer of the atmosphere with an average altitude of 13km and extends roughly up to 8km near the poles and about 18km at the equator.
**This layer contains 75% of the total gaseous mass, dust particles, and water vapours.
**The layer experiences a gradual decrease in temperature with increase in altitude with a constant rate at 1-degree Celcius for every 165m called Normal lapse rate.
** All weather and climatic phenomenon have occurred in this layer.
**The troposphere is separated from the next layer by Tropopause.
(ii) STRATOSPHERE-
**Stratosphere extends above the tropopause to about 50km high and lacks any atmospheric turbulence, so jet airways are flown in this layer.
**The lower stratosphere sometimes have cirrus clouds.
**The air temperature is steadily increased with altitude due to the absorption of UV rays by Ozone layer, but the temperature never go above the melting point of water.
**Stratosphere is separated from mesosphere by Stratopause which has the stable thermal condition.
**The lower portion of the Stratosphere having a maximum concentration of ozone is called Ozonosphere.
(iii) MESOSPHERE-
**Mesosphere is the frigid atmospheric layer with the coldest atmospheric conditions extending up to 80km from Stratopause.
**Temperature decreases here with altitude and reaches up to -100 degrees Celcius.
**Meteors burn up in this layer as Shooting stars.
**This layer is separated from the thermosphere by Mesopause.
**The upper layer of the Mesosphere is marked by Mesopause.
(iv) THERMOSPHERE-
**Thermosphere extends from mesopause to about 640km altitude. Its lower layer is called Ionosphere due to the presence of free radicals or ionic particles.
**In the lower thermosphere above mesosphere, low Earth orbit spacecraft fly, and Astronauts conduct spacewalks from the space shuttle.
**In this layer temperature increases rapidly with altitude due to the interaction of ionosphere and electromagnetic radiations from the outer space of the sun. But molecules are, so far spread apart that we wouldn't feel the heat of the atmosphere.
(v) IONOSPHERE-
**Ionosphere extends from 80km to 640 km above the mesopause.
**Radiowaves transmitted from the earth are reflected back to the earth by this layer and temperature starts increasing with altitude.
**Ionosphere has many thermal layers that are D layer, E layer, etc. and separated from each other by Gradients called Pause.
(vi) EXOSPHERE-
**It represents the uppermost layer of the atmosphere extends beyond 640km where gases are most rarefied and abundance in electrically charged particles.
**In the exosphere molecules have enough kinetic energy to escape gravity and fly off into space.
**Helium disappears here.
On the basis of uniformity, the atmosphere is divided into two zones:
(i)HOMOSPHERE-
**It is the zone where uniform mixing and composition of gases and other constituents are found.
**Major gases are Nitrogen, oxygen, Argon, Carbon dioxide, Water vapour, and particulates are also found here with uniformity in distribution.
**The layer extends up to 88km from the surface of the earth and includes Troposphere, Stratosphere, and Mesosphere.
**The concentration of the major gases remains relatively constant due to convective currents and effects of heat and moisture on airflow patterns near the Earth's surface.
(ii)HETEROSPHERE-
**It is the zone that extends from 88km above to about 10000km and includes both Ionosphere and exosphere and the air is no longer uniform in this zone.
**Due to the lack of convective heating at this height, the material found in the heterosphere is layered according to its mass.
**The lower heterosphere consists of a small area dominated by ionic elements or free radicals and free electrons called the ionosphere.