Here the immediate reference is to some of the useful phenomena of nature like the rain, day and night, and the source of creation of creatures which is the water. Not only the maintenance of life depends on water that all the creatures, is said, to have basically been created from it. If we consider the movements of the clouds overhead, we soon come to know that there is an object or aim behind every movement or any change that takes place up there. All the movements are reasonable and seems that each one is a part of a general plan fulfilled by a great and infinite intelligence.
We see during the winter that, thin layers of clouds move gently around, in various fantastic shapes and forms, as if they are various creatures moving over us! They then join together and heap up and become a dark huge body, which covers the shining face of the sun. It eventually pours down droplets of rain, and wonderful crystals of snow, and sometimes awful hail-stone, for our punishment. Such phenomena are sometimes accompanied by blinding flashes of lightening that almost snatches the eyes.
In the second clause of the above verse (NO.43) mention is made of mountainlike clouds in the sky from which showers of hail-stone may come to afflict some people, and turn away from some other.
This is because the clouds, as seen from over by an aeroplane, have not a level surface and seem to be mountains and valleys from far above.
Hail-stones is precipitation in the form of ice particles that range in diameter from less than 1/4 inch, to more than 5.
These grains of ice may be spherical, conical, or quite irregular. Typically they consist of alternating layers of clear and opaque ice.
Hail-stone often form in the thunderstorms that have rising air current strong enough to suspend ice particles while they grow by the accretion of water droplets at subfreezing temperature.
Opaque ice is formed by the accretion of small sparse droplets, and clear ice by accretion of larger quantities of cloud moisture.
Hail-stone may seriously damage plant life, and large hail-stones can injure people or animal, or even it may damage buildings. Hail-stone is also an aviation hazard, and it is one reason why pilots avoid thunderstorm:ِ
``....And He sends down from the sky hail-stones out of the mountainlike clouds, pelting with it whom He Will, and turning away from whom He pleases.''
The next verse refers to another important sign of God, which is the change of night to day and day to night. One of the two, lengthens while the other shortens, and vice versa.
They gradually change in length and bring forth the various seasons. The existence of both, night and day, as well as their changes in length, temperature, and whatsoever, is indeed vital to the natural life of Man:ِ
``Allah changes the night and day. Verily in that changes there are lessons for those who have eyes to learn.''
