Abhishek Srivastava is teaching live on Unacademy Plus
Most important topies of 0 Gegraphy Atmosphere-
ABHISHEK SRIVASTAVA . UPSC CSE Category leader at Unacademy . Top educator with more than 2.9 mn views Appeared in UPSC CSE Mains twice . Qualified SSC CGL, IBPS PO, IIT JEE . Courses: Crash Course on Geography with MCQs for Prelims 2018 @Unacademy.com/Plus o o Geography PYQ series with concepts o Crash courses - Polity, Modern, Ancient & Medieval History o Ncert Class VI History,Delhi Sultanate o Essay writing o Editorial analysis and News nalysis- Nov & Oct'1 https://unacademy.com/userlabhishek6077
Some related concepts with respect to Atmosphere: Heat budget Incoming heat being absorbed by the Earth, and outgoing heat escaping the Earth in the form of radiation are both perfectly balanced. If they were not balanced, then Earth would be getting either progressively warmer or progressively cooler with each passing year. This balance between incoming and outgoing heat is known as Earth's heat budget. Albedo:- 1. It is a measure of how much light that hits a surface is reflected back without being absorbed 2. It is a reflection coefficient and has a value less than one 3. The reflected amount of radiation is called as the albedo of the earth. 4. Albedo for different surface is shown diagramatically in the next slide (very important from prelims perspective)
Some related concepts with respect to Atmosphere Albedo for different surfaces in percentage wise: 1, Snow cover-70-90% 2, Sand-20-30% 3. Grass-14-35% 4. Dry Ground:-15-25% 5, wet Ground:-10% Insolation:The energy received by the earth's surface in the form of short waves is termed as Incoming Solar Radiation or Insolation. Normal Lapse Rate:-Temperature decreases with increase in height at the rate of 6.5 degree Celsius per 1000metres (which happens in troposphere and mesosphere) Temperature Inversion:- As stated above, Temperature decreases with increase in height at the rate of 6.5 degree Celsius per 1000metres (normal lapse rate), but some times this normal trend is reversed under special circumstances and thus the temperature increases upward upto a few kilometers from the surface of the earth. This is Temperature inversion or negative Lapse rate
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Humidity and precipitation in the atmosphere Humidity refers to amount of moisture content or water vapor present in the air in gaseous form at a particular time and place. Different types of humidity 1.) Absolute humidity:-The total weight of moisture content per volume of air at definite temperature 2.)Specific Humidity:-Defined as mass of water vapor in grams contained in 1 kg of air 3.)Humidity Capacity:-The moisture content of the air is measured in grain per cubic foot or in gram per cubic centimeter 4.) Relative Humidity:- Is the ratio of Absolute Humidity/Humidity capacity *100, that is ratio of amount of water vapor actually present in air to the maximum amount of the water vapor the air can hold
Precipitation and rainfall in the atmosphere Precipitation is any type of water that forms in the earth's atmosphere and then drops on to the surface of the earth in the form of drizzle, rainfall etc.. Types of precipitation: 1. 2. 3. 4. Rainfall: drop size of water more than 0.5 mm Drizzle: light rainfall; drop size less than 0.5 mm Snowfall: fine flakes of snow fall when the temperature is less than 0 C Hail: precipitation in the form of hard rounded pellets is known as hail; 5 mm and 50 mm 5. Sleet:- frozen raindrops and refrozen melted snow; mixture of snow and rain or merely partially melted snow.
Precipitation and rainfall in the atmosphere Different Types of Rainfall: Convectional Rainfall Orography Rainfall Monsoonal Rainfall
1.) Convectional Rainfall:- The, air on being heated, becomes light and rises up in convection currents. As it rises, it expands and loses heat and consequently, condensation takes place and cumulous clouds are formed. The droplets that reach the earth is the rainfall due to con Sun heats the land and the air above Warm air rises, cools Rain can then occur forming clouds Sea Land 2.lOrographic Rainfall-When moist air or saturated air mass gets lifted and moves over the mountain ranges, there is a precipitation formed and it is called as orographic rainfall.
Jet streams in the atmosphere: Jet streams are Circumpolar (situated around or inhabiting around one of the earth's poles), 1. 2. narrow, concentrated bands of 3. meandering, 4 upper tropospheric, 5. high velocity winds, 6. geostrophic streams, 7. bounded by low speed winds and 8. are a part of upper level westerlies. 4. upp Significance of the jet Streams in the upper layer of the atmosphere 1. Helpful in aviation/Flight Movement, air travel becomes easier 2. Helpful in weather forecasting 3. Helpful in maintenance of atmosphere stability