O espring or March quinox of the northern hemisphere starts today, Friday, March 20th. When they are precisely 14:46 (time in mainland Portugal and Madeira Archipelago, 13:46 in the Azores Archipelago) Spring begins in the Northern Hemisphere (the Southern Hemisphere sees the beginning of autumn).
The term equinox derives from Latin, combining two terms in the same word: equal which means “equal” and Nox which means night, consisting of a remarkable moment on several levels. In theory, this is the time of year when the natural day and night have the same duration: approximately 12 hours each.
According to the Lisbon Astronomical Observatory (OAL), day and night have approximately the same duration due to the fact that at the time of the equinoxes the Sun, seen from planet Earth, “crosses the plane of the celestial equator, that is, the line of the terrestrial equator that is projected onto the celestial sphere”. Spring will continue for approximately 92 days, until the summer solstice or June occurs, which will mark the beginning of the summer season.
Astronomical spring versus climatological spring
Spring as a season begins and ends at different times, depending on the perspective of the scientific discipline used. For meteorology and climatology, spring in the northern hemisphere (meteorological or climatological spring), where Portugal is located, began on March 1st and will end on May 31stcovering all the months of March, April and May.
This definition is based on climatological and statistical parameters, encompasses months with similar characteristics in relation to this transition season (average precipitation and temperature) and provides better data analysis and seasonal forecasting.
Naturally, this is different from the concept of astronomical spring. For astronomy, spring only started today – Friday, March 20th – based on the instant of equinoxsince the seasons are based on the position of the Earth in relation to the Sun.
Customs, traditions and curiosities of the spring equinox
Spring start day is a historically important date. The arrival of this season of the year marks the decrease in the frequency of situations of unstable or adverse weather conditions, discomfort and lack of agricultural production, aspects most characteristic of winter.
Throughout much of the 20th century, this astronomical phenomenon was celebrated every March 21st. Although, Since 2008, the equinox has occurred on the 20th. This is due to the fact that the Earth’s translation period does not last exactly one year. Thus, until the year 2044, the equinox will occur every 20th, varying between the 19th and 20th from that year onwards. It should also be added that from the year 2100 this date will once again be between the 20th and 21st.
Traditionally, spring symbolizes the rebirth of nature. Flowers are once again ‘painting’ the landscapes, the length of the natural day is increasing and in ancient times festivals of fertility and abundance were celebrated. General cleaning of the houses is carried out, after a long winter period in which it was really uncomfortable to air them out.
Furthermore, eggs are a symbol of the equinox, closely associated with the issue of fertility. There is even an ancient myth that stated that at the exact moment the equinox occurs, it becomes possible to balance an egg on its base on a flat surface, because it is at that moment that day and night are in perfect balance.
