Tag: elements of weather and climate : temperature

• Globally water occupies a major portion. Water constitutes 96.5 % on the earth and rest is land. Of the total water content fresh water contributes a very little portion of 2.5%. Fresh water sources include:
  
• Groundwater - water found in shallow aquifers beneath the earth's surface. This water is generally found at depths up to around 2,000 feet deep.
  
• Precipitation: It is nothing but the rain water which is an important source of fresh water. In fact it is the purest natural source of fresh water.
  

• A rain gauge is a little cylindrical container that collects rainwater falling into it to measure the rainfall during a particular period.
• Certain conditions are needed to be fulfilled for accurate measurement of rainfall viz water should not enter into the rain gauge from any source other than direct rainfall and the rain gauge instrument has to be kept at a certain height. 

• Mawsynram located in Meghalaya, India receives 11871 mm of annual rainfall which is highest in the world thus option D is the correct answer.
• Cherrapunjee is located only  15 km away from Mawsynram is in second place in terms of the amount of rainfall.

Absolute humidity is the total amount of water vapor present in the air. In other words, the weight of water vapor per volume of air is referred to as the absolute humidity. It is usually expressed as grams of water vapor per cubic meter of air. Absolute humidity varies with the expansion or contraction of air, even though the amount of water vapor is constant.

Convectional rainfall occurs when surface of the earth is heated up by the sun. The warm surface also heats up the air. As air rises it cools down and begins to condensate. Further rising and cooling causes a large amount of condensation to occur and rain is formed. Conventional rainfall usually occurs in the equatorial region.

Rainbow is caused by reflection, refration and dispersion of light in water droplets resulting in a spectrum of light appearing in the sky. It is a meterological phenomenon. It is caused in the presence of sunlight. It appears in the section of sky which is directly opposite to the sun.

B.  Latent Energy

 Latent heat is the energy absorbed by or released from a substance during a phase change from a gas to a liquid or a solid or vice versa.  If a substance is changing from a solid to a liquid, for example, the substance needs to absorb energy from the surrounding environment in order to spread out the molecules into a larger, more fluid volume.  If the substance is changing from something with lower density, like a gas, to a phase with higher density like a liquid, the substance gives off energy as the molecules come closer together and lose energy from motion and vibration.

Absolute humidity is the actual amount of water vapour present in air. It is expressed as grams of moisture per cubic meter of air. It is calculated by finding the mass of water vapor in an area and dividing it by the mass of air in the same area. Absolute humidity may range from 0 gram per cubic meter in dry air to 30 grams per cubic meter when the vapour is saturated at 30 $^oC$. As the temperature of air increase, humidity also increases.

The phenomenon by which gaseous molecules convert from gaseous state to liquid state is called condensation. It is the process by which water vapor in the air is changed into liquid water. Condensation is responsible for the formation of clouds. That’s why it is crucial to the water cycle. These clouds produce precipitation which is the primary route for water to return to the Earth’s surface through rain. Condensation is the opposite of evaporation.