1930 dust bowl in the great bowl was cause by

The dust bowl was caused by an over farming of soil and an intense drought. This in turn caused the soil to become very dry and sand like, which cause dust storms, which is how it got its name "The Dust Bowl"

Explanation:

You can look this up about anywhere really, but we just finished a section on the dust bowl in my history class.

it would lead to upper respiratory infections and pneumonia.

the second type of galaxy is called a barred spiral, which has a thing called a bar straddling the nucleus