The spring equinox and the fall equinox, when the sun crosses the equator and day and night are of equal length, respectively, typically take place on March 21 and September 23, respectively.
A significant time in our orbit around the solar is marked by the equinoxes. The rising sun switches from the northern to the southern hemisphere at the September equinox.
The vernal equinox is another name for it in the southern hemisphere. The fall equinox is when it happens in the northern hemisphere. Only during the equinox does the sun emerge in the east and set in the west.
What is Declination?
The latitude at which it looks like the sun is directly overhead is referred to as declination. Latitudes in the northern hemisphere are expressed using positive declination, while those in the southern hemisphere are expressed using negative declination. This changes consistently throughout the year and can be used to identify our seasons.
The solstices and equinoxes of the earth’s orbit around the sun are used by astronomers to properly time the seasons. According to this calendar, the vernal equinox marks the beginning of spring in the southern hemisphere.
Due to the earth’s elliptical trajectory and increased speed during our summer, this results in our winter lasting 93 days and our summer lasting 89 days.
For practical reasons, climatologists average climate data over each month of the year; therefore, the southern hemisphere spring is defined as the months from September to November.
Keep in mind that summer lasts 90 days by this calculation. (91 days in a leap year). This technique of season-marking is more common in New Zealand than observing equinoxes and solstices. Certainly, it extends summer by one or two days.
Also Read: How to Calculate Solar Panel Tilt Angle?
How is the length of a day longer than a 24-hour period?
Generally speaking, the length of a day is about 7 minutes longer than a 24-hour period. This is due to the fact that sunrise is defined as the moment when the top limb of the sun is just beginning to show on the horizon, and sunset is defined as the moment when the top limb of the sun has completely dipped below the horizon.
The sun emerges and vanishes when its center is just below the horizon due to the refraction of the atmosphere and the fact that the sun is not just a point. The extra sunshine is explained by this. The equilux is the term used to characterize the day when there are twelve hours between sunrise and sunset.
