Simplify the following text for a Grade 11 native English-speaking person.
Original: A polar low is a small-scale , short-lived atmospheric low pressure system ( depression ) that is found over the ocean areas poleward of the main polar front in both the Northern and Southern Hemispheres .
Simplified: A polar low is a small sized and short-lived atmospheric low pressure system that is found over the ocean areas pole ward of the main polar front in both the Northern and Southern Hemispheres .