You will be given a definition of a task first, then some input of the task.
In this task, you are given a paragraph, and your task is to construct a question from the given passage. Construct question in such a way that (i) it is well explained in the paragraph, (ii) the words may/may not be present in the paragraph, (iii) it should start with what/how/describe. Avoid creating a question that (i) is just relevant to one or two sentences, and (ii) not relevant to passage. 

Water in the clouds becomes very cold. The cold water forms ice crystals. The ice crystals grow by absorbing surrounding water droplets. Form snowflakes. The snowflakes fall to the ground. 
Output:
How does snow form?