<p>This all depends on the context in which the word is used.</p>

<p>From an astronomical perspective, the solstices are midsummer and midwinter, and the equinoxes are the middle of autumn and the middle of spring.</p>

<p>However, the seasons, as perceived in terms of weather, lag somewhat behind the astronomical seasons (presumably this is due to the thermal mass of the planet?). For example, most people of my acquaintance think of northern-hemisphere summer as occupying approx. June/July/August, putting the June solstice near the start of it. Therefore, colloquially, the solstices and equinoxes seem to roughly match up with the starts of the seasons, and hence are often treated that way.</p>

<p>Why does this apply to the equinoxes more than the solstices? (citation needed - but  purely from personal observation, many people think of the summer solstice as "midsummer" but the spring equinox as "the start of spring"). I'm speculating, but my guess is that midsummer and midwinter are really obvious to anybody keeping an eye on the sky (when the sun reaches its greatest or least north/south extent, or "when the days start getting shorter", or whatever). The equinoxes are slightly harder to judge, and so aren't noted in quite the same way.</p>

CC BY-SA 3.0
2014-09-17T19:51:30.233Z
Meteorological seasons (NH) start on 1 Mar (spring), 1 June (summer), 1 Sep (autumn) and 1 Dec (winter).
casey
CC BY-SA 3.0
2014-09-16T11:21:44.930Z
2014-09-17T11:58:14.077Z
2014-09-17T11:58:14.077Z
Semidiurnal Simon
<p>There are three main ways to reckon <a href="http://en.wikipedia.org/wiki/Season" rel="nofollow noreferrer">seasons</a>:</p>
<ul>
<li><strong>Solar.</strong> The 3 months with the greatest insolation are designated summer, so the solstices and equinoxes fall in the middle of the season. In the Celtic calendar, summer started on 1 May; in the traditional Chinese calendar it is <a href="https://en.wikipedia.org/wiki/Lixia" rel="nofollow noreferrer">5-7 May</a>. The cultural 'Midsummer' and 'Midwinter' festivals reflect this.</li>
<li><strong>Astronomical.</strong> The solstices and equinoxes are the starts of the seasons, with summer starting on about 21 June (<a href="http://en.wikipedia.org/wiki/Solstice" rel="nofollow noreferrer">it varies</a>). Its use dates back at least to the Romans, and it's used in most western cultures today (apparently not in Russia, Australia, or New Zealand).</li>
<li><strong>Meteorological.</strong> This is what professional meteorologists use (e.g. <a href="http://www.metoffice.gov.uk/climate/uk/summaries/2014/summer" rel="nofollow noreferrer">UK Met Office</a>), and is based on the prevailing weather on land at mid-latitudes. Seasons are 3 months long and summer starts on 1 June.</li>
</ul>
<p>I've tried to illustrate the relationships with insolation and temperature here:</p>
<p><img src="https://i.sstatic.net/gWNb5.png" alt="Different ways to reckon seasons" /></p>
<p>There are some other ways too:</p>
<ul>
<li><strong>Ecological.</strong> Scientists who study the behaviour of organisms (hibernation, blooming, etc.) adapt to the local climate, <a href="http://seasons2011.blogspot.ca/2011/06/ecological-seasons.html" rel="nofollow noreferrer">sometimes using 6 seasons</a> in temperature zones, or only 2 in polar and tropical ones.</li>
<li><strong>Agricultural.</strong> This would centre around <a href="http://en.wikipedia.org/wiki/Growing_season" rel="nofollow noreferrer">the growing season</a> and therefore, in North America and Europe at least, around frost.</li>
<li><strong>Cultural.</strong> What people think of as 'summer', and what they do outdoors (say), generally seems to line up with local weather patterns. In my own experience, there's no need for these seasons to even be 3 month long; When I lived in Calgary, summer was July and August (hiking), and winter was December to March (skiing). <a href="http://www.bom.gov.au/iwk/yawuru/index.shtml" rel="nofollow noreferrer">Here's another example</a> of a 6-season system, and <a href="http://www.bom.gov.au/iwk/maung/index.shtml" rel="nofollow noreferrer">a 3-season system</a>, from the Aboriginal people of Australia, all based on weather.</li>
</ul>
<p>Why do systems with later season starting dates prevail today? Perhaps because at mid-latitudes, the <a href="http://en.wikipedia.org/wiki/Seasonal_lag" rel="nofollow noreferrer">seasonal lag</a> means that the start of seasonal weather is weeks later than the start of the 'insolation' period. In a system with no <a href="http://en.wikipedia.org/wiki/Heat_capacity" rel="nofollow noreferrer">heat capacity</a>, there would be no lag. In systems with high heat capacity, like the marine environment, the lag may be several months (Ibid.). Here's what the lag looks like in three mid-latitude cities:</p>
<p><img src="https://i.sstatic.net/jOEgw.png" alt="Seasonal lag. Licensed CC-BY-SA by EOEarth" /></p>
<p>The exact same effect happens on a <a href="http://en.wikipedia.org/wiki/Diurnal_temperature_variation" rel="nofollow noreferrer">diurnal</a> (daily) basis too — the warmest part of the day is often not midday (or 1 pm in summer). As with the seasons, there are lots of other factors too, but the principle is the same.</p>
<p>These aren't mutually exclusive ways of looking at it — there's clearly lots of overlap here. Cultural notions of season are surely rooted in astronomy, weather, and agriculture.</p>

CC BY-SA 3.0
2016-09-26T21:57:51.873Z
How did you create the illustration of the 3 main ways of defining a season?
G. Gip
CC BY-SA 4.0
2014-10-09T13:00:24.110Z
2021-02-26T11:44:25.833Z
2021-02-26T11:44:25.833Z
Matt Hall
<p>In the United States, the upcoming autumnal equinox is marked on most calendars as the "first day of autumn." Similarly the solstices are commonly called the "first day of summer" and "first day of winter." However in most other languages -- and even in older discussions in English -- the solstices have names like "Midsummer's Day" and "Midwinter's Day."</p>

<p>Is there some sound reason (e.g. typical temperatures, asymmetrical sunrise/sunset times, thermal inertia, etc.) to consider a solstice as the first day of a new season, rather than the middle? </p>

<p>Also (perhaps less on-topic) is there any record of when the change in nomenclature took place in the U.S.? Are there similar discrepancies in other English-speaking countries or in other cultures?</p>

CC BY-SA 3.0
2014-09-15T22:17:19.147Z
"In many cultures, solstices/equinoxes traditionally determine the midpoint of the seasons, which can be seen in the celebrations called midsummer and midwinter. In this vein, the Japanese celebrate the start of each season with an occurrence known as Setsubun. The cumulative cooling and warming that result from the tilt of the planet become most pronounced after the solstices, leading to the more recent custom of using them to mark the beginning of summer and winter in most countries of Central and Northern Europe, as well as Canada, USA and New Zealand." http://en.wikipedia.org/wiki/Solstice
f.thorpe
CC BY-SA 3.0
2014-09-15T22:18:38.160Z
This question was asked in the English stack exchange.  In fact... your question is really about language not science. http://english.stackexchange.com/questions/117183/etymology-of-midsummer-why-is-the-first-day-of-summer-called-middle-of-summ
f.thorpe
CC BY-SA 3.0
2014-12-14T06:06:11.970Z
Related: http://earthscience.stackexchange.com/q/2133/725
Gimelist
<terminology><meteorology>
Equinoxes and solstices: start of the season or mid-season?
rob
# Equinoxes and solstices: start of the season or mid-season?

(Asked by: username_0 on 2014-09-12)

In the United States, the upcoming autumnal equinox is marked on most calendars as the "first day of autumn." Similarly the solstices are commonly called the "first day of summer" and "first day of winter." However in most other languages -- and even in older discussions in English -- the solstices have names like "Midsummer's Day" and "Midwinter's Day."

Is there some sound reason (e.g. typical temperatures, asymmetrical sunrise/sunset times, thermal inertia, etc.) to consider a solstice as the first day of a new season, rather than the middle?

Also (perhaps less on-topic) is there any record of when the change in nomenclature took place in the U.S.? Are there similar discrepancies in other English-speaking countries or in other cultures?

**Tags:** terminology, meteorology

> **Comments:**
> **username_1**: "In many cultures, solstices/equinoxes traditionally determine the midpoint of the seasons, which can be seen in the celebrations called midsummer and midwinter. In this vein, the Japanese celebrate the start of each season with an occurrence known as Setsubun. The cumulative cooling and warming that result from the tilt of the planet become most pronounced after the solstices, leading to the more recent custom of using them to mark the beginning of summer and winter in most countries of Central and Northern Europe, as well as Canada, USA and New Zealand." http://en.wikipedia.org/wiki/Solstice  
> **username_1**: This question was asked in the English stack exchange.  In fact... your question is really about language not science. http://english.stackexchange.com/questions/117183/etymology-of-midsummer-why-is-the-first-day-of-summer-called-middle-of-summ  
> **username_2**: Related: http://earthscience.stackexchange.com/q/2133/725  

---

## 2 answers

### Answer by username_5 on 2014-10-09. Score: 25 | Accepted answer

There are three main ways to reckon [seasons](http://en.wikipedia.org/wiki/Season):

* **Solar.** The 3 months with the greatest insolation are designated summer, so the solstices and equinoxes fall in the middle of the season. In the Celtic calendar, summer started on 1 May; in the traditional Chinese calendar it is [5-7 May](https://en.wikipedia.org/wiki/Lixia). The cultural 'Midsummer' and 'Midwinter' festivals reflect this.
* **Astronomical.** The solstices and equinoxes are the starts of the seasons, with summer starting on about 21 June ([it varies](http://en.wikipedia.org/wiki/Solstice)). Its use dates back at least to the Romans, and it's used in most western cultures today (apparently not in Russia, Australia, or New Zealand).
* **Meteorological.** This is what professional meteorologists use (e.g. [UK Met Office](http://www.metoffice.gov.uk/climate/uk/summaries/2014/summer)), and is based on the prevailing weather on land at mid-latitudes. Seasons are 3 months long and summer starts on 1 June.

I've tried to illustrate the relationships with insolation and temperature here:

![Different ways to reckon seasons](https://i.sstatic.net/gWNb5.png)

There are some other ways too:

* **Ecological.** Scientists who study the behaviour of organisms (hibernation, blooming, etc.) adapt to the local climate, [sometimes using 6 seasons](http://seasons2011.blogspot.ca/2011/06/ecological-seasons.html) in temperature zones, or only 2 in polar and tropical ones.
* **Agricultural.** This would centre around [the growing season](http://en.wikipedia.org/wiki/Growing_season) and therefore, in North America and Europe at least, around frost.
* **Cultural.** What people think of as 'summer', and what they do outdoors (say), generally seems to line up with local weather patterns. In my own experience, there's no need for these seasons to even be 3 month long; When I lived in Calgary, summer was July and August (hiking), and winter was December to March (skiing). [Here's another example](http://www.bom.gov.au/iwk/yawuru/index.shtml) of a 6-season system, and [a 3-season system](http://www.bom.gov.au/iwk/maung/index.shtml), from the Aboriginal people of Australia, all based on weather.

Why do systems with later season starting dates prevail today? Perhaps because at mid-latitudes, the [seasonal lag](http://en.wikipedia.org/wiki/Seasonal_lag) means that the start of seasonal weather is weeks later than the start of the 'insolation' period. In a system with no [heat capacity](http://en.wikipedia.org/wiki/Heat_capacity), there would be no lag. In systems with high heat capacity, like the marine environment, the lag may be several months (Ibid.). Here's what the lag looks like in three mid-latitude cities:

![Seasonal lag. Licensed CC-BY-SA by EOEarth](https://i.sstatic.net/jOEgw.png)

The exact same effect happens on a [diurnal](http://en.wikipedia.org/wiki/Diurnal_temperature_variation) (daily) basis too — the warmest part of the day is often not midday (or 1 pm in summer). As with the seasons, there are lots of other factors too, but the principle is the same.

These aren't mutually exclusive ways of looking at it — there's clearly lots of overlap here. Cultural notions of season are surely rooted in astronomy, weather, and agriculture.

> **Comments:**
> **username_6**: How did you create the illustration of the 3 main ways of defining a season?  

---

### Answer by username_3 on 2014-09-16. Score: 8

This all depends on the context in which the word is used.

From an astronomical perspective, the solstices are midsummer and midwinter, and the equinoxes are the middle of autumn and the middle of spring.

However, the seasons, as perceived in terms of weather, lag somewhat behind the astronomical seasons (presumably this is due to the thermal mass of the planet?). For example, most people of my acquaintance think of northern-hemisphere summer as occupying approx. June/July/August, putting the June solstice near the start of it. Therefore, colloquially, the solstices and equinoxes seem to roughly match up with the starts of the seasons, and hence are often treated that way.

Why does this apply to the equinoxes more than the solstices? (citation needed - but purely from personal observation, many people think of the summer solstice as "midsummer" but the spring equinox as "the start of spring"). I'm speculating, but my guess is that midsummer and midwinter are really obvious to anybody keeping an eye on the sky (when the sun reaches its greatest or least north/south extent, or "when the days start getting shorter", or whatever). The equinoxes are slightly harder to judge, and so aren't noted in quite the same way.

> **Comments:**
> **username_4**: Meteorological seasons (NH) start on 1 Mar (spring), 1 June (summer), 1 Sep (autumn) and 1 Dec (winter).  

---

