TASK DEFINITION: In this task, we ask you to rewrite a sentence in simple English without changing its general meaning. Essentially, you want to make the sentence easier to read by using simpler words, utilizing more straightforward sentence structures, and omitting non-essential information etc.
PROBLEM: The effect of mountain chains on prevailing winds is to carry warm air belonging to the lower region into an upper zone , where it expands in volume at the cost of a proportionate loss of temperature , often accompanied by precipitation in the form of snow or rain .

SOLUTION: The effect of mountain chains on winds is to carry warm air belonging to the lower region into an upper zone , where it expands and loses heat , and drops snow or rain .

PROBLEM: The guinea pig or domestic guinea pig ( " Cavia porcellus " ) , also known as cavy or domestic cavy , is a species of rodent belonging to the family Caviidae and the genus " Cavia " .

SOLUTION: Guinea pigs are " Cavia porcellus " , a kind of rodent .

PROBLEM: The National Guard is a joint activity of the United States Department of Defense ( DoD ) composed of reserve components of the United States Army and the United States Air Force : the Army National Guard and the Air National Guard , respectively .

SOLUTION:
The United States National Guard is an organization of the United States Army and the United States Air Force .