First Alert Weather In-Depth: Measuring the start of the spring season
ROCHESTER, N.Y. – Nothing like the change of seasons and it is certainly significant from an astronomical point of view. But what is the actual meaning for this planetary designation? We can start with the specific scientific name for the start of spring and that is the vernal equinox.
If you remember back to your earth science school days, you probably recall those imaginary lines that go around the surface of the Earth. There is the tropic of Cancer, that is the longest day of the year and the tropic of Capricorn, which is the shortest day of the year. Those lines are just a reference point to what we are talking about, which is the equator. Monday it is the equator where the direct rays of the sun are located and hence the reference to “equinox”. This is the day when we receive roughly equal amounts of daylight and nighttime hours. Naturally, as the sun moves into the northern hemisphere, the days are getting longer.
This change is even more evident when you go back to December 21, the first day of winter season. On that day the angle of the sun was only 23 degrees at solar noon and we measured less than nine hours of possible daylight. Now, the angle of the sun stands at 47 degrees above the horizon. If you do the math, we have added three hours and nine minutes of new daylight over this 13 week time period.
Spring has sprung with eventually warmer weather on the way!