ATMOSPHERE
   The gaseous or air envelope of the physical environment surrounding the earth and bound to it, because of earth’s gravitational attraction (about 800 Kms.) constitutes the atmosphere. It is made of air, which is a mixture of oxygen (21%), nitrogen (78%), carbon dioxide (0.037%) and other gases like hydrogen, helium, argon, neon, krypton, xenon and ozone. It also contains water vapor and dust particles. Around 90% of the atmosphere by weight lies in the lowest 15 km (9 miles) above the surface, which actually supports all life on the earth. It also protects the life on earth from harmful solar radiation either by reflecting them back or by absorbing them. Atmosphere is divided into: Troposphere, Stratosphere, Mesosphere, Ionosphere and Exosphere.

PRECIPITATION
    Any liquid or solid form of water particles that falls from the atmosphere and reaches the Earth's surface is known as precipitation. Precipitation can occurs in a variety of forms such as drizzle, hail, rain, sleet or snow.

RAIN
   Rain develops when growing water droplets become too heavy to remain in the cloud and as a result, fall toward the surface as rain. Rain can also begin as ice crystals that collect each other to form large snowflakes. As the falling snow passes through the freezing level into warmer air, the flakes melt and collapse into raindrops.

SNOW
   When small ice crystals inside the clouds collide and stick together they form Snowflakes. Most snowflakes melt on their way to the ground and fall as rain. But only when the air near the ground is cold enough snowflakes fall as snow. (Precipitation formed by the sublimation of water vapor into solid crystals at temperatures below freezing).

HAIL
   Hail is a large frozen raindrop produced by intense thunderstorms, some thunderstorms provide environment where snow and rain can coexist. As the snowflakes fall, liquid water freezes onto them forming ice pellets that continue to grow as more and more droplets are accumulated.

CLIMATE
   The statistical collection and representation of the weather conditions for a specified area during a specified time interval (usually decades) describes the word climate. The word climate is derived from the Greek klima, meaning inclination. The properties that characterize the climate are thermal (temperatures of the surface air, water, land, and ice), kinetic (wind and ocean currents, aqueous humidity, cloudiness and cloud, water content, groundwater, lake, lands, and water content of snow on land and sea ice), and static (pressure and density of the atmosphere and ocean, salinity of the oceans, and the composition of the dry air). The various physical processes such as precipitation, evaporation, infrared radiation, etc interconnect the various components of the climate, its behavior and its properties.
   Climate is always dynamic, it vary from place to place and from country to country around the world. Many things influence a place's climate such as distance from the equator and the local topography (natural features). Mountain ranges and Coastal areas often have a different climate to those of inland. Climates also vary over time and change very gradually over decades and centuries. Human activity also greatly influences the climate.

WIND
   Wind is simply air in motion. Air flows in relation to the earth's surface, generally horizontally and from high pressure to low-pressure area. Winds are described by the direction they blow from - an easterly wind flows from the east, a westerly from the west. Prevailing winds are arranged in a series of belts around the globe. This pattern is the result of the different amounts of solar heating the place gets depending upon the topography. The four parameters used to measure wind are: direction, speed, character, and shifts

CLOUD
   A cloud is a collection of minute particles of water or ice suspended in the air.Clouds form when the invisible water vapor in the air condenses into visible water droplets or ice crystals. (the moist air is pushed upward and it cools. This is because cool air holds less water vapor than warm air, so the vapor condenses into either liquid or ice. These condensed particles are what we see as the clouds). The cloud is, however, mostly air - the drops or ice particles often make up as little as one millionth of the volume! When a cloud forms at relatively warm temperatures, the particles are usually tiny liquid drops. At very low temperatures, the particles are usually ice. Clouds can exist in a variety of shapes and sizes. Clouds are active elements that play a crucial role in determining climatic conditions on our planet. One important area in which clouds play a role is in the energy balance of the Earth, Another important role of clouds in the Earth system involves water transport. Clouds are made of ice or liquid water, and they help redistribute water through the air, returning it to the surface as rain or snow.

   Clouds are classified into different forms depending upon the level at which they are present (distance from the earth surface). If the bases of the clouds are between surface to 7,000 feet the clouds are known as Low-level clouds. Low clouds are mostly composed of water droplets. However, when temperatures are cold enough, these clouds may also contain ice particles and snow.    If the clouds typically appear between 7,000 to 17,000 feet then they are known as Mid-level clouds. Because of their lower altitudes, they are composed primarily of water droplets. These Mid-level clouds can also be composed of ice crystals when temperatures are low enough.
   High-level clouds gets formed above 17,000- 35,000 feet, since the temperatures are so cold at such high elevations these clouds are primarily composed of ice crystals. High-level clouds are typically thin and white in appearance.
   The most familiar of the clouds is the Vertically Developed Clouds (cumulus) cloud. Generated most commonly through either thermal convection or frontal lifting, these clouds can grow to heights in excess of 39,000 feet (12,000 meters), releasing incredible amounts of energy through the condensation of water vapor within the cloud itself.