Fact 1: Temperature falls from the equator to the poles.

Fact 2: Sun's rays are perpendicular to the equator.

Given the two facts above, answer the question "Temperatures fall towards the poles as the sun's rays are no longer what?" with the following options: 
- kinetic energy
 - negative
 - visible energy
 - harmful substances
 - perpendicular
 - heat energy
 - direct energy
 - reflecting light


 

     perpendicular    