Tomorrow marks the first day of fall–the Autumnal Equinox–where the entire planet had equal amounts of daylight and darkness. Well, not so fast. As a kid, I would hear this all the time (that & Clean your room) but once I get to college and was exposed to the science in greater detail, it ate away at that statement. Here is what is happening:
The Earth, as it orbits the sun is tilted on its axis (roughly 23 degrees). This tilted Earth is why we have our seasons!! (we’re actually closer to the sun in January than July). On the orbit around the sun, the northern hemisphere of the Earth is tilted toward the sun–summer, and then 6 months later, the northern hemisphere is tilted away from the sun, hence winter. But in-between are the other two seasons–spring & fall. On the equinoxes (Equi-Nox–from latin….Equal Night) , the Earth is evenly exposed to sunlight. Then why not 12 hours of daylight and 12 hours of darkness across the entire planet? So, there are a few things that are happening here:
Sunrise/sunset adds some daylight to the day as they are calculated when the upper edge of the sun is visible on the horizon–not the center of the sun’s disk. Also, refraction (the bending of light) causes that edge of the sun to be visible from earth before it actually is…adding eve more daylight) and finally, your latitude determines when you reach that 12/12 mark (For Boston, it’s September 25th, while in Panama City it’s on September 26th).
Regardless of the equinox happening tomorrow, it’s looking warm–quite warm actually. Here is what I’m forecasting for high temps tomorrow afternoon:
Impressive, most impressive. Fear not fall lovers….your time is coming behind a cold front Friday evening. Temps this weekend will only reach the 60s for highs (normal high is 71) with morning lows down into the 40s.