How it works: Spring Equinox brings warmth to the Big Country
ABILENE, Texas (KTAB/KRBC) – Monday not only marked the first day students went back to class after spring break, but it was also the official last day of winter. Tuesday’s Spring Equinox is the official start of spring because the sun crosses over earth’s equator, moving from south to north.
Earth’s tilt on its axis is what causes this northward shift of the sun’s path across our sky at this time of year. Earth’s tilt is now bringing spring and summer to the Northern Hemisphere.
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To be more specific, worldwide, Tuesday is considered the March Equinox. While spring begins for us in the northern hemisphere, fall begins and a shift towards winter occurs in the southern hemisphere. It is the complete opposite in places like Australia and South America.
The sun will cross the celestial equator (a line directly above Earth’s equator), slating the Spring Equinox for 10:06 p.m. CDT Tuesday night. So, how does this affect us here in the Big Country?
Twice a year on the spring and fall equinoxes, the world supposedly receives exactly 12 hours of day and 12 hours of night. But, that’s not precisely true. In fact, there are about eight more minutes of daylight at mid-latitude regions (highlighted in red below) on the day of an equinox.
The first reason is because the sun is a disk, not a point of light like stars. Most almanacs regard sunrise as when the leading edge of the sun first touches the eastern horizon. They define sunset as when the sun’s trailing edge finally touches the western horizon.
This alone provides an extra two-and-a-half, to three minutes of daylight at the mid-latitudes regions. The second reason is because Earth’s atmosphere refracts (bends) sunlight.
It advances the sunrise and delays the sunset, adding nearly another six minutes of daylight at mid-latitude regions. Hence, more daylight than night at the equinox.
Weather Update: Warmer & drier conditions to start the week
Now, we already know unofficial spring weather has been around the Big Country for a while, but what should we expect for the new season?
As far as the weather conditions for this week, a warming trend is beginning Monday. Temperatures will be in the 70s by Wednesday and 80s by Friday and on into the weekend.
The upper level low that has been nearly stationary over the Desert Southwest will finally weaken and eject east across Texas as an open wave Wednesday into Thursday. This will bring us another chance for some showers and a few thunderstorms to the area.
However, latest models show much of the precipitation associated with this system remaining north and east of the area. Rain chances remain on the lower side as of now about 20 to 40% for Wednesday afternoon into Thursday morning.
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