The two younger members of the party were not to be blamed for feeling pretty well frightened by this time.  It was one thing to be cutting through the fleecy white clouds of a calm day, and quite another to go stabbing through murky black ones which were rolling angrily, ejecting both wind and rain, and spitting out vicious roars and jagged streaks of pale-blue flame.  One moment they would be in gloom; the next instant a cloud would be rent asunder with a ripping, tearing sound, and the whole turbid, boiling sky-universe would be bathed in the ghostly light.  What a weird, fantastic, chaotic world they were in!