Wednesday, March 19, 2008
Vernal Equinox
Spring is Here
The Vernal Equinox occurs tonight at 1:48 in the morning. This marks the beginning of astronomical spring. The sun is directly over the equator making it equal day and night for each hemisphere. We go into spring while the southern hemisphere heads into fall. You might ask why the sunrise and sunset times are not exactly twelve hours apart on the first day of spring. The earth’s atmosphere bends the light so there is not exactly twelve hours between the sunrise and sunset on Thursday. As we move toward summer the sun’s angle will continue to rise. The angle of the sun is the key to climate. Yes, the days get longer and the jet streams retreat to the north but the angle of the sun is what drives climate. The higher the angle, the more overhead, the stronger the sun’s rays will be. You might also be asking yourself why it’s not the same time and same day every year. Well, the reason goes back to my leap year column. The solar year is about 365 and a quarter days so the time and date of spring and of all of the seasons can vary about a day or so. It still looks like March is going to stay below average in terms of temperatures for the remainder of the month. March came in like a lamb it reserves the right to go out like a lion. ¶ 5:00 PM
The Vernal Equinox occurs tonight at 1:48 in the morning. This marks the beginning of astronomical spring. The sun is directly over the equator making it equal day and night for each hemisphere. We go into spring while the southern hemisphere heads into fall. You might ask why the sunrise and sunset times are not exactly twelve hours apart on the first day of spring. The earth’s atmosphere bends the light so there is not exactly twelve hours between the sunrise and sunset on Thursday. As we move toward summer the sun’s angle will continue to rise. The angle of the sun is the key to climate. Yes, the days get longer and the jet streams retreat to the north but the angle of the sun is what drives climate. The higher the angle, the more overhead, the stronger the sun’s rays will be. You might also be asking yourself why it’s not the same time and same day every year. Well, the reason goes back to my leap year column. The solar year is about 365 and a quarter days so the time and date of spring and of all of the seasons can vary about a day or so. It still looks like March is going to stay below average in terms of temperatures for the remainder of the month. March came in like a lamb it reserves the right to go out like a lion. ¶ 5:00 PM
