Philadelphia Weather: Balloon rocket experiment demonstrates Friday's wind

PHILADELPHIA - To explain why it got windy Friday afternoon, we did an experiment on FOX WEATHER PHILLY. On the show, Scott Williams and Drew Anderson launched a balloon rocket to show how cold air weighs more than warm air.

When you have more air in one spot, like cold air, and less air in another spot, like warm air, wind is created.

Picture two water bottles connected together: one bottle has a lot of water and the other bottle has only a little water. This will cause water to flow from the bottle with more to the bottle with less.

That flowing water is just like the blowing wind Philadelphia got Friday afternoon.

Air moved from where it weighed more to where it weighed less, causing wind.

On Thursday, the Philadelphia area had milder weather. Highs were in the upper 40s and low 50s.

That warmer air, which weighs less, is now to the south of Philly.

A cold front came in with Friday's morning showers, leaving cold air for the Philadelphia area in its wake.

This colder, heavier air is flowing toward the milder, lighter air down by Washington D.C.

As that air moves, it creates wind.

So that's why Philly saw cold winds coming down from the north Friday afternoon. If our cold air were much colder, it would be much windier.

The more opposite in temperature the cold and warm air is, the faster the wind blows. Air moves a lot faster when much heavier, colder air is right next to lighter, warmer air.

If you're wondering why air and water move in the same way, technically speaking, air is a fluid. So, literally, air flows just like water.

FOX WEATHER PHILLY is our 3:30 PM weekday weather show that you can watch exclusively on FOX LOCAL, our free smart TV app, or on the livestream on the FOX29.com homepage.