So in case nobody noticed, a few days ago the temperature dropped from levels typical of mid-June to somewhere off the charts that I would estimate to be pretty darn close to absolute zero. Actually, the temperature is now just slightly below the average for the season, but why did it get really cold really fast? To start, I'm sure the jet stream had something to do with it, pushing cold arctic air into upstate NY, and pushing out the warmer tropical air we had been experiencing. But more importantly, its now late October and it gets cold around this time every year. But why is that? First of all, the earth rotates on a tilted axis; so in other words the axis on which the earth spins is not perpendicular to the plane on which path of earth's orbit around the sun lies. The ends of the axis of rotation are the geographical north and south poles, not to be confused with magnetic poles. As the earth travels in a slightly elliptical path around the sun, the geographical north pole always points in the same direction in space, so during the summer in the northern hemisphere the pole is pointing in the general direction of the sun while in the winter the pole is pointing away from the sun. As a result, the angle at which the sun's rays strike the earths surface is closer to 90 degrees and less light waves are reflected into space, causing more energy to strike the earth, causing the temperature to rise. The opposite happens in the winter, and this is the reason why it is summer in the northern hemisphere while it is winter in the southern hemisphere. Therefore, the reason why it got cold is because light isn't hitting the earth like it used to. For a visual representation of this, watch this video.