Do your remember the story of Elijah in 1 Kings 17-18? It did not rain for three years and the Northern Kingdom suffered from severe famine. Wherever there is not enough rain it becomes a dry desert. The balance of life is that we both need rainy days and sunny days to have a well-balanced atmosphere. Time comes when the human body has too much heat that it is time to cool it down and to replenish the bodies of water.
Basic science tells us that it is the dark clouds that are the rain clouds. The white clouds do not bring rain. As King Solomon mentioned in Ecclesiastes 3:1-8 there is a time for everything. If there is a time for sunshine then there is also a time for rainy days. Trials and tribulations may come but there is also a time for ease. Both of these are necessary to accept both tribulations and ease as part of life. It is time to simply remember that when God brings the dark clouds, it is those dark clouds that bring in the water.
On that dark day of Calvary, it was indeed a cloudy day. It was a dark day indeed but it was that day when Jesus Christ the Son of God died for sin out of His love for man. It was on that dark and stormy day when the Son of God paid for the sins of man once and for all (Hebrews 10:12). The same sacrifice was to be done only once and never to be repeated again. Those dark clouds contained a lot of water and it rained. But it was in that rain that maybe anybody can see the message of forgiveness and new life because the sacrifice on the cross is finished.