Why were King Ferdinand and Queen Isabella of Spain willing to finance Columbus? They were free to do so after recapturing Granada
They did not want Columbus to sail for England.
The Portuguese were gaining an advantage over Spain.

from the conditions of the working class in england by friedrich engels,the main idea is :

the causes of the dust bowls were severe droughts,   lands became dry and hard, temperature was higher than usual, hot and dry conditions killed crops, high winds. because of those factors, the winds kicked up dry soil and created clouds of dust.