Reflection and absorption by the atmosphere prevent some from reaching earth's surface.

Radiation

Explanation:

The atmosphere act as a protective blanket around the earth surface against the harmful incident raidations from the sun. It absorbs some radiations also reflect some of them so as to maintain the heat energy balance on earth. Protects the radiations coming direct contact with earth surface.

most cajuns resided in acadiana, where their descendants are still predominant

answer; an active listener;