It’s here…it’s finally here. Spring! OK, I know what you’re saying… ” silly meteorologist..it’s been spring for a while now.”. Yes, our weather has been very spring like lately, but officially this morning, the earth’s tilt was so that the sun’s direct rays were over the Equator and thus officially making today the 1st day of spring. From now until June 21st, the earth will continue to tilt so that the days gets longer and the nights get shorter.
How many of you were taught that on the equinox (vernal or fall), that we have exactly 12 hours of daylight and 12 hours of dark? If you thought that was true, think again. Because today in Oklahoma City we actually have almost 12 hours and 10 mins of daylight. So, what happened here? Blame it on our earth. You see, the globe is not exactly your perfect circle (it’s a sphere). And, we have this little thing above us known as “an atmosphere”.
Sunrise is defined as the moment the sun hits the top edge of the horizon and the sunset is defined as the moment the top of the sun falls below the horizon. The problem however is that due to the way the light is bent through the atmosphere, the illusion is that the sun is still up in the sky when in reality, it has already set.
Take that into account as well as physical features such as mountains and valleys and you’ll discover that the amount of daylight has to take into account many different things other than just the fact that the sun is over the equinox or Tropic of Capricorn.
This year’s spring equinox is also quite unique. Growing up many of us were taught that the equinox usually falls on the 20th or the 21st right? But if you’re in The Mountain Time Zone or Pacific Time Zone, your equinox actually happened on the 19th. (For Oklahoma, it was just minutes after midnight). Today’s arrival of spring is actually the earliest we’ve seen since 1896.
Why so early? A year usually (not this year since it’s a Leap Year) has an odd number of days. You don’t have an even number of days nor do you have an even number of days in a season. Take this into account:
The current seasonal lengths for 2012 in the Northern Hemisphere are:
Winter: 88.994 days Spring: 92.758 days Summer: 93.651 days Autumn: 89.842