Twice a year, around March 20 or 21 and again on September 22 or 23, the sun shines directly on the equator and the length of day and night are nearly equal in all parts of the world. These two days are known as the March(vernal or spring in the northern hemisphere) equinox and the September equinox.
The word "equinox" derives from the Latin words meaning "equal night" and refers to the time when the sun crosses the equator. At such times, day and night are everywhere of nearly equal length everywhere in the world.
During the equinox, the length of night and day across the world is nearly, but not entirely, equal. This is because the day is slightly longer in places that are further away from the equator, and because the sun takes longer to rise and set in these locations. Furthermore, the sun takes longer to rise and set farther from the equator because it does not set straight down - it moves in a horizontal direction.
Moreover, there is an atmospheric refraction that causes the sun's disk to appear higher in the sky than it would if earth had no atmosphere.
During the March equinox, the length of daylight is about 12 hours and eight to nine minutes in areas that are about 30 degrees north or south of the equator, while areas that are 60 degrees north or south of the equator observe daylight for about 12 hours and 16 minutes. Many regions around the equator have a daylight length about 12 hours and six-and-a-half minutes during the March equinox.
The vernal equinox occurs in the spring while the autumnal equinox occurs during fall (autumn). These terms are derivatives of Latin. It is important to note that the northern hemisphere's vernal equinox is in March while its autumnal equinox is in September. In contrast, the southern hemisphere's vernal equinox is in September and its autumnal equinox is in March.
This distinction reflects the seasonal differences when comparing the two hemispheres. timeanddate.com refers to the two equinoxes simply as the March and September equinoxes to avoid false assumptions that spring is in March and fall (autumn) is in September worldwide. This is simply not the case.
Spring Season is a particular type of season that is experienced in the temperate climatic zones. Spring is an intermediate seasonal phase in between winter and summer. Spring signifies the emergence of new life. Spring months are the blossoming months that bring meaningful growth and rejuvenation in its wake. Spring enriches natural beauty and it seems as if nature is dressed in a beautiful green gown.
This season arrives during different parts of the year in the North and South of the world. Places, which are situated in the north experience the spring season from March to May while in the southern part of the world, September to November is the springtime. Vernal Equinox indicates the arrival of spring season while the Summer Solstice announces its departure.
Extreme weather conditions characterize the spring season. This is due to the fact that during this season, the warm winds coming from the lower regions are accompanied by the cold air which originates from the Polar Regions. During the spring season, days are longer and the weather is severe. The seas and rivers are full because the snow begins to melt. Rainfall is also heavy often leading to serious flood situations. Floods are most common in the hilly areas. In addition to all this, tornado, hailstorms and heavy downpour are also common features during the spring season. In fact, end of spring is the time when hurricane arrives almost without any warning.
Next time when you notice a newly budding leaf, be assured that spring has arrived.
Spring is the time for a celebration of planting and of the greening of the Earth. The supermarket is a sign in itself, as the produce department begins to fill with fresh fruits and vegetables. People start to talk about having 'Spring Fever' and doing 'Spring cleaning', as the brighter sunshine provides a needed morale boost.