Cyclone      A cyclone is a general term for a weather system in which winds rotate inwardly to an area of low atmospheric pressure. The rotation is usually counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere of the Earth. Size      The largest low-pressure systems are cold core polar cyclones and extra tropical cyclones which lie on the synoptic scale (up to 5000km in diameter).       Warm-core cyclones such as tropical cyclones, mesocyclones, and polar lows lie within the smaller mesoscale (up to 500km in diameter). Subtropical cyclones are of intermediate size (upto 2000km in diameter). Terminologies      Hurricanes and typhoons are the same weather phenomenon: tropical cyclones.  A tropical cyclone is a generic term used by meteorologists to describe a rotating, organized system of clouds and thunderstorms that originates over tropical or subtropical waters and has closed, lo...

  General weather system of India Weather & Climate      Climate refer to the sum total of weather condition and variation over large area for a longer period of time. Weather refers to the state of the atmosphere over an area at any point of time. The elements of weather and climate are the same, i.e. temperature, atmospheric pressure, wind, humidity and precipitation. On the basis of the generalized monthly atmospheric conditions year is divided into seasons.      India situated in the northern hemisphere; the tropic of cancer passes through the middle part of the country. As a result the southern half of the country has a tropical climate.  During the winter season in the Northern hemisphere, Northern half of the country is warmer than the areas of similar Latitude about 3° to 8 °  Celsius. This is due the fact that the Himalayas check the cold polar air mass entering into India. In other countries like USA the polar air mass inva...

 Cloud formation & Precipitation Cloud formation     Condensation of water above the Earth surface creates clouds. In general cloud develop in any air mass that becomes saturated (relative humidity become 100%).      Saturation can occur by way of atmospheric mechanism that causes the temperature of an air to be cooled to its dew point.  The following processes can be responsible for the formation of the clouds.      W hen air is forced to rise because of the physical presence of elevated land. As the parcel of air rises, it cools due to adiabatic expansion at a rate of approximately 10° C / km.       The development of clouds and resulting heavy quantities of precipitation along SW coast of India, during the SW Monsoon, is due to these processes.      A rain shadow is a patch of land that has been forced to become a desert because mountain ranges blocked all plant-growing, rainy weather. On o...

 G reenhouse gases & Global warming 30% of the portion of energy is reflected or scattered back to the space  Stratosphere absorbs about 19% of the available energy (like UV) is absorbed by the clouds, gases (like ozone), and dust. About the 51% of the sun’s radiation reaches the surface of the earth, and this can heat the surface to an average temperature of -20°C. If this is the case, water will remain as ICE all over the earth. There will be no water in liquid or in gaseous form, as a result Earth will appear as white Ball. Greenhouse Effect     Solar radiation is absorbed by the surface and re-emitted back to the atmosphere as longer wavelength. Absorption of longer wave radiation causes additional heat energy to the atmosphere. Over 90% of energy is directed back to the earth surface, and again this process is repeated, until no longer wave is available for absorption.    And this process contributes the heating up of earth to an average te...

Hypsography of the continents and ocean floor       Hypsometry is the measurement of land elevation (relative to mean sea level). Bathymetry is the underwater equivalent. A hypsometric curve is a histogram or cumulative distribution function of elevations in a geographical area.         Continental margin Continental margin, the submarine edge of the continental crust distinguished by relatively light and isostatically high-floating material in comparison with the adjacent oceanic crust. It is the name for the collective area that encompasses the continental shelf, continental slope, and continental rise. Continental margins are about 28% of the oceanic area. A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water known as a shelf sea. Much of these shelves has been exposed during glacial periods.           The continental shelf (approx 0.1°), steep continental s...