Air might feel like nothing to you and me, but it is actually super heavy. In fact, the pressure caused by all those gases in the atmosphere stacked on top of each other creates a great deal of pressure-about 14.7 pounds pressing on every inch of our body. We don't notice it because we are used to it.
But not all areas have the same exact air pressure. Some areas have more pressure than their surroundings, and some areas have less.
Those that have less pressure are called low-pressure systems. Low-pressure systems "suck" air into them because nature wants everything to have equal pressure. By doing this, they generally create winds and undesirable weather.
High-pressure systems, on the other hand, have more air pressure than their surroundings. That means they are constantly pushing air away from them into the areas that have lower pressure. They are often times associated with clear blue skies.
A polar vortex is a semi-permanent, massive low-pressure system that hovers over the poles of our planet.