July 7, 2013

How to measure rainfall in an area?

Rainfall can be measured by means of an instrument called the Rain Gauge and rainfall is measured in millimeters. It consists of a cylinder in which a bottle is placed. This bottle is fitted with a funnel at its mouth. So the rain water falling into it does not evaporate.
  • The rain water is measured in a graduated glass the area of whose mouth bears a fixed ratio to the area of the mouth of the funnel.
  • Most of the times this ratio is 1 : 10.
  • One cubic cm of rain in this graduated glass denotes 1 mm rainfall.
rain guage - How to measure rainfall in an area

Example: Thus, if one says that 10 mm of rain has fallen, we mean that if the rain, which has fallen over a level piece of ground and had remained there without being lost by evaporation, flowing or seeping into the earth, the height of that water would have been 10 mm.
The daily record of rainfall helps us to get the total rainfall in a year. The rainfall is shown on maps by means of lines drawn to join all places with the same rainfall.

How to Calculate Mean Daily Temperature?
Add the maximum and the minimum temperatures of that day and divide it by two.
Example: If on any day (say 30th Oct.. 2003) the maximum temperature in Delhi was 32°C and the minimum was I6°C. It means the Mean Temperature on that day was:
(32+16)/2 = 24° C

How to Calculate Mean Monthly Temperature?
Add the average mean temperatures of all days of the month and divide the sum by the number of days in that month.
How to Calculate Mean Annual Temperature?
Add the average mean temperature of all months of the year and divide the sum by 12. The result would be the Mean Annual Temperature of that particular place.
How to Calculate  Daily or Diurnal Range of Temperature?
 If we take the difference between the maximum and the minimum temperatures of a day, it gives us the Daily or the Diurnal Range of Temperature. daily range of temperature can be directly noted from the thermograph
The difference between the maximum and the minimum temperatures during a month gives us the Monthly Range of Temperature.
The difference between the average temperatures of the hottest and the coldest months is known as the Annual Rangeof Temperature. Generally the months of July and January are selected for this purpose.


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