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Why We Have Summer: The Summer Solstice
June 20, 2022 at 09:56 PM EDT
By WeatherBug Meteorologist, Alyssa Robinette
While some people consider the first day of summer to be June 1st, most people consider the start of summer to be the solstice, which occurrs at 5:13 a.m. EDT Tuesday. This is because, astronomically, the Northern Hemisphere receives the longest stretch of sunlight on this day.
Solstices occur because Earth’s axis of rotation is tilted about 23.4 degrees relative to Earth’s orbit around the sun. This tilt drives our planet’s seasons, as the Northern and Southern Hemispheres get unequal amounts of sunlight over the course of the year. From March to September, the Northern Hemisphere is tilted more towards the sun and therefore gets more hours of sunlight, driving its spring and summer. Meanwhile, from September to March, the Northern Hemisphere is tilted away and there gets fewer hours of sunlight, which drives the autumn and winter seasons.
The Earth’s axis is tilted the closest towards the sun twice each year, and these moments are called solstices. During the Northern Hemisphere’s summer solstice, the sun appears directly over the Tropic of Cancer, which is around 23.5 degrees north latitude (north of the equator). Then, during the Northern Hemisphere’s winter solstice, the sun appears directly over the Tropic of Capricorn, which is around 23.5 degrees south latitude (south of the equator).
Many refer to Astronomical Summer on June 21st, as the first “official” day of summer. Most meteorologists will argue that summer has been well under way by then and they have been enjoying at least three weeks- - if not longer-- of "summer" already.
Meteorologists observe seasons over different time periods. Meteorological summer begins on June 1, fall begins September 1, winter begins December 1 and spring begins March 1. It makes tracking seasonal weather statistics, such as average temperatures and precipitation, much easier by having a pre-defined start and end to the season. It’s much more cumbersome to track the specific dates of the solstices and equinoxes each year, which vary by a day here and there.
A second reason meteorologists mark the seasons the way they do is that weather-wise, it makes more sense. For example, much of the Northern Hemisphere is entrenched in a hot weather pattern by June 1. Waiting until June 20 or 21 would capture the first heat wave in Texas, for instance, as a spring phenomenon, which doesn’t accurately represent the season.
Also, winter weather typically unfolds around December 1, at least in parts of the country. So, waiting until December 20 or 21 to begin collecting winter temperature and precipitation records each year means that early month cold blasts or snow amounts would be logged as a fall phenomenon. In fall, heat begins to wane by September 1 and by March 1, the first day of meteorological spring, mild surges start to become a regular occurrence and the seasonal severe weather threats grows.
Image by Arek Socha from Pixabay
Solstices occur because Earth’s axis of rotation is tilted about 23.4 degrees relative to Earth’s orbit around the sun. This tilt drives our planet’s seasons, as the Northern and Southern Hemispheres get unequal amounts of sunlight over the course of the year. From March to September, the Northern Hemisphere is tilted more towards the sun and therefore gets more hours of sunlight, driving its spring and summer. Meanwhile, from September to March, the Northern Hemisphere is tilted away and there gets fewer hours of sunlight, which drives the autumn and winter seasons.
The Earth’s axis is tilted the closest towards the sun twice each year, and these moments are called solstices. During the Northern Hemisphere’s summer solstice, the sun appears directly over the Tropic of Cancer, which is around 23.5 degrees north latitude (north of the equator). Then, during the Northern Hemisphere’s winter solstice, the sun appears directly over the Tropic of Capricorn, which is around 23.5 degrees south latitude (south of the equator).
Many refer to Astronomical Summer on June 21st, as the first “official” day of summer. Most meteorologists will argue that summer has been well under way by then and they have been enjoying at least three weeks- - if not longer-- of "summer" already.
Meteorologists observe seasons over different time periods. Meteorological summer begins on June 1, fall begins September 1, winter begins December 1 and spring begins March 1. It makes tracking seasonal weather statistics, such as average temperatures and precipitation, much easier by having a pre-defined start and end to the season. It’s much more cumbersome to track the specific dates of the solstices and equinoxes each year, which vary by a day here and there.
A second reason meteorologists mark the seasons the way they do is that weather-wise, it makes more sense. For example, much of the Northern Hemisphere is entrenched in a hot weather pattern by June 1. Waiting until June 20 or 21 would capture the first heat wave in Texas, for instance, as a spring phenomenon, which doesn’t accurately represent the season.
Also, winter weather typically unfolds around December 1, at least in parts of the country. So, waiting until December 20 or 21 to begin collecting winter temperature and precipitation records each year means that early month cold blasts or snow amounts would be logged as a fall phenomenon. In fall, heat begins to wane by September 1 and by March 1, the first day of meteorological spring, mild surges start to become a regular occurrence and the seasonal severe weather threats grows.
Image by Arek Socha from Pixabay