Title Meteorology Part-1.pdf ✅

www.iaritoppers.in Whatsapp : +91-9694095242 Page | 1 Meteorology 5 th Edition 2024
www.iaritoppers.in Whatsapp : +91-9694095242 Page | 2  Greek word “Meteoro” means ‘above the earth’s surface’ (atmosphere) &“logy” means ‘indicating science’. Branch of science dealing with that of atmosphere is known as meteorology. 1. Weather: Physical state of the atmosphere at a given place and given time. Eg. Cloudy day 2. Climate: Long term regime of atmospheric variables of a given place or area. Eg. Cold season Agro-meteorology:  A science concerned with the application of meteorology to the measurement and analysis of the physical environment in agricultural systems. The word ‘Agro meteorology’ is the abbreviated form of agricultural meteorology. Composition of atmosphere: The following all the different gases that are present in percentage by volume approximately. Nitrogen (N2) = 78.08 Oxygen (O2) = 20.95 Argon (Ar) =0.93 CO2 =0.0412 Neon (Ne) = 0.0018
www.iaritoppers.in Whatsapp : +91-9694095242 Page | 3 Composition by weight (%): Vertical Layers of atmosphere based on temperature:  On the basis of vertical temperature variation, the atmosphere is divided into different spheresor layers. A. Troposphere:  From Surface upwards temperature decreases with altitude.  Under normal conditions the height of the troposphere changes from place to place and season to season.  The average height of this lower most layer of the atmosphere is about 18 km above the mean sea level; at the equator, it is 16-18 km and 7-8 km at the poles.  The word “Trop” means mixing or turbulence and “sphere” means region.  Various types of clouds, thunderstorms, cyclone and anticyclones occur in this sphere because of the concentration of almost all the water vapour and aerosols in it. So, this layer is called as “seat of weather phenomena”.  In this layer, about 75 per cent of total gases and most of the moisture and dust particles present.  At the top of the troposphere, there is a shallow layer separating it from the stratosphere which is known as the “Tropopause “.  The temperature at the tropopause is of the order of -80 ̊C over the equator and around -56 ̊C over the poles.  The troposphere is the densest part of the atmosphere. Nitrogen (N2) = 75.52 Oxygen (O2) = 23.14 Argon (Ar) =1.28 CO2 =0.045
www.iaritoppers.in Whatsapp : +91-9694095242 Page | 4 B. Stratosphere:  This layer exists above the tropopause (around 20 km onwards) and extends to altitudes of about 50-55 km.  This layer is called as “Seat of photochemical reactions”.  It is dust free, cloud-free and warmest layer.  The pressure of this layer is 1/1000th of sea level.  The temperature remains practically constant at around 20 km and is characterized as iso- thermal because air is thin, clear, cold and dry near tropopause.  The temperature of this layer increases with height and also depends upon the troposphere because the troposphere is higher at the equator than at the poles.  Less convection takes place in the stratosphere because it is warm at the top and cold at the bottom.  There is also persistence of circulation patterns and high wind speeds.  The upper boundary of the stratosphere is called the stratopause.  This rise in temperature is also due to the absorption of ultraviolet radiation in the ozone layer between, say, 20 and 50 km. This region sometimes gets rapidly warmed, mainly in the higher