Question

Just as precise measurements are necessary in science, it is equally important to be able to make rough estimates of quantities using rudimentary ideas and common observations. Think of ways by which you can estimate the following (where an estimate is difficult to obtain, try to get an upper bound on the quantity):

the total mass of rain-bearing clouds over India during the Monsoon

 

Answer 1

During monsoons, a metrologist records about 215 cm of rainfall in India i.e., the height of water column, h = 215 cm = 2.15 m

Area of country, A = 3.3 × 10¹² m²

Hence, volume of rain water, V = A × h = 7.09 × 10¹² m³

Density of water, ρ = 1 × 10³ kg m^–3

Hence, mass of rain water = ρ × V = 7.09 × 10¹⁵ kg

Answer 2

The average rainfall of nearly 100 cm or 1 m is recorded by meteorologists, during Monsoon, in India.

If A is the area of the country, then A = 3.3 million sq. km = 3.3 x 10⁶(km)2 = 3.3 x 10⁶ x 10⁶m²= 3.3 x 10¹²m²

Mass of rain-bearing clouds = area x height x density = 3.3 x 10¹² x 1 x 1000 kg = 3.3 x 10¹⁵ kg.