How do i calculate the annual rainfall of a climate table
Answers
Explanation:
First of all, “The mean of the annual rainfalls over a period of 30-35 years is known as Average annual Rainfall
Average annual rainfall for a place is generally calculated by averaging the last 30-35 years of annual rainfall.
Annual rainfall is the sum of daily rainfall, that can be calculated from raingauge records. Here, while calculating average annual rainfall one must take the length of period into account. One cannot simply average the 10 years of data to state the average rainfall. It has to be 30-35 years.
(The reason behind choosing the 30-35 years is to represent the climatic condition of that place.)
But what we want is the average annual rainfall for a city or a geographical area. That is a much more complex problem. A geographical area is likely to be a catchment area, such as a river basin or valley where, perhaps, several rivers flow in with water from different mountains. Water levels will be the result of total annual rainfall in the catchment area, plus that which arrives from the parts of the surrounding mountains that pour water into the valley. All that rainfall matters, and it can’t be measured everywhere.
If we take several measurements at different locations in the catchment area, we can’t simply average them. Some areas may be more representative, and therefore more significant, than others. So annual rainfall will be based on a model of a lot of weighted averages.
(Rainfall is measured in millimeters (mm). The word Annual means Yearly. So then we look at Average, the sum of a group of items, that is divided by the number of items! To calculate the average we could look at a location over say 30-35 years to get us a good working average.)