The presence of clouds upon your sky, and trials in your path, is the very best evidence that you are following the pillar of cloud, and walking in the presence of God. They had to enter the cloud before they could behold the glory of the transfiguration, and a little later that same cloud became the chariot to receive the ascending Lord, and it is still waiting as the chariot that will bring His glorious appearing.
Still it is true that white "clouds and darkness are round about His throne, mercy and truth" are ever in their midst, and "shall go before His face."
Perhaps the most beautiful and gracious use of the cloud was to shelter them from the fiery sun. Like a great umbrella, that majestic pillar spread its canopy above the camp, and became a shielding shadow from the burning heat in the treeless desert. No one who has never felt an Oriental sun can fully appreciate how much this means -- a shadow from the heat.
So the Holy Spirit comes between us and the fiery, scorching rays of sorrow and temptation.