Let's break this down so you can completely understand it:
THE DUST BOWL DEFINITION:
"The Dust Bowl, also known as the Dirty Thirties, was a period of severe dust storms..." -Wikipedia
DUST STORM DEFINITION:
A wide-spread of strong winds of dust, soil, and sand.
So.. The series of dust storms kills crops (PEOPLE EAT CROPS), and caused a drought. The moral of the story is there was too many dust storms coming to one area at in a short period of time (which caused the dust bowl).