In the eleventh verse of Surat az-Zukhruf, rain is defined as water sent down in due measure. The verse is as follows: He sends down (from time to time) water from the sky in due measure, and We raise to life therewith a land that is dead. Even so will you be raised (from the dead). (Surat az-Zukhruf, 11) This measure mentioned in the verse has to do with a couple of characteristics of rain. First of all, the amount of rain that falls on the earth is always the same. It is estimated, that in one second, 16 million tones of water evaporate from the earth. This number is equal to the amount of water that drops on the earth in one second. This means that water continuously circulates in a balanced cycle according to a measure. Another measure related with rain is about its falling speed. The minimum altitude of rain clouds is 1,200 meters. When dropped from this height, an object having the same weight and size as a rain drop, would continuously accelerate and fall on the ground with a speed of 558 km/h. Certainly, any object that hits the ground with that speed would cause great damage. If rain happened to fall in the same way, all harvested lands would be destroyed, residential areas, houses, and cars would be damaged, and people would not be able to walk around without taking extra precautions. What is more, these calculations are made just for clouds at a height of 1,200 meters; there are also rain clouds at altitudes of 10,000 meters. A rain drop falling from such a height could normally reach a very destructive speed. But this is not how it works; no matter from what height they fall, the average speed of rain drops is only 8-10 km/h when they reach the ground. The reason for this is the special form they take. This special form increases the friction effect of the atmosphere and prevents acceleration when the rain drops reach a certain speed limit. (Today parachutes are designed by using this technique.) This is not all about the measures of rain. For instance, in the atmospheric layers where it starts to rain, the temperature may fall as low as 400 C below zero. Despite this, rain drops never turn into ice particles. (This would certainly mean a fatal threat to the living things on the earth.) The reason is that the water in the atmosphere is pure water. As is well-known, pure water hardly freezes even at very low temperatures
Posted on: Sun, 06 Apr 2014 14:44:15 +0000