“There is no real ‘correct’ answer” to when spring begins, Stardome Observatory\u2019s Josh Aoraki says. Photo \/ Michael Craig<\/p>\n
\u201cIn saying that, there are three main factors that I\u2019d take into consideration – meteorological, astronomical, and ecological\/social.\u201d<\/p>\n
MetService meteorologist Mmathapelo Makgabutlane said the astronomical definition tracks seasons according to the earth\u2019s position around the sun, a practice used for thousands of years.<\/p>\n
Astronomical spring begins on the spring equinox – when the sun passes directly over the earth\u2019s equator – which falls between September 22 and 23 in the Southern Hemisphere.<\/p>\n
\u201cThis means spring goes until the summer solstice around 21 or 22 December,\u201d Makgabutlane said, noting that our winter is also four days longer than the Northern Hemisphere\u2019s.<\/p>\n
\u201cThe earth\u2019s orbit is slightly oval-shaped [rather than a perfect circle] and the earth speeds up a bit during our summer.\u201d<\/p>\n
Astronomers therefore mark seasonal changes by correlating the position of Earth around the sun with four divisions in the calendar year.<\/p>\n
These divisions – the solstices and equinoxes- work as seasonal tentpoles.<\/p>\n
\u201cBy this definition, spring for us will begin on the equinox which starts on September 23 and ends on the solstice which is on December 21,\u201d Aoraki said.<\/p>\n
Meteorological spring runs from September 1 to November 30, while astronomical spring begins on September 23. Photo \/ 123rf<\/p>\n
What do meteorologists think?<\/p>\n
Meteorologists and climatologists use the meteorological definition of the seasons – the ones we\u2019re most familiar with – which are directly tied to the calendar months.<\/p>\n
\u201cBy this definition, spring runs from September 1 to November 30, with meteorological summer starting on December 1 to the end of February,\u201d Makgabutlane said.<\/p>\n
\u201cUsing the calendar months has a practical use for things like long-term tracking of climate records since the seasons always fall on the same days.\u201d<\/p>\n
By following the meteorological definition, the Southern Hemisphere has a 92-day winter and 90-day summer, with an extra summer day during a leap year.<\/p>\n
What about the environment\u2019s role?<\/p>\n
Nature also plays a part in determining when seasons start and end, and many cultures use environmental cues or tohu (signs) like the flowering of a plant or migrating birds to mark the occasion.<\/p>\n
\u201cPlants and animals are able to sense when the right time is to do what they need to do, and sometimes that\u2019s earlier, other times that\u2019s later,\u201d Aoraki said.<\/p>\n
Ecological signs, like the welcoming of lambs, also indicate spring’s arrival. Photo \/ Sylvie Whinray<\/p>\n
\u201cHere in Aotearoa, the call of the p\u012bp\u012bwharauroa\/shining cuckoo is often used as a sign of spring when the birds return to New Zealand as it begins to get warmer,\u201d Makgabutlane added.<\/p>\n
Meanwhile, New Zealand\u2019s seasonal temperature changes often lag by a few weeks, so the changing of seasons can almost feel muted to begin.<\/p>\n
\u201cOur temperatures are closely tied to the ocean, which warms and cools more slowly than land, so it takes a little longer for temperatures to catch up.\u201d<\/p>\n
Does it matter which one I use?<\/p>\n
\u201cAlthough the two definitions have the seasons start and end on different days, broadly speaking, they both cover the warmest, coldest, and transition times of the year,\u201d Makgabutlane said.<\/p>\n
\u201cWhich one people use is down to whichever is most relevant for them. As a meteorological agency, MetService uses meteorological spring for practical and climate record keeping purposes.\u201d<\/p>\n
While each definition serves its own purpose, Aoraki said they exist as \u201carbitrary ways for humans to understand the division of time and help us organise our lives around them\u201d.<\/p>\n
\u201cThe earth\u2019s tilt, equinoxes and solstices, and seasons will change over aeons, as will the meteorological markers of a season, so neither would be relevant in thousands of years.\u201d<\/p>\n
Tom Rose is an Auckland-based journalist who covers breaking news, specialising in lifestyle, entertainment and travel. He joined the Herald in 2023.<\/p>\n