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Fig. 1

This is a diagram of the seasons. Note that, however the Earth turns, the north pole will be dark, and the South Pole will be illuminated; see also arctic winter. In addition to the density of the rays, the dissipation of light in the atmosphere is greater when it comes in at a shallow angle.

Fig. 2

Another diagram of the seasons

As the Earth revolves around the Sun, seasons alternate in the northern and southern hemispheres.

A season is one of the major divisions of the year. Typically, the year is divided into four seasons: spring, summer, autumn (fall), and winter. Some cultures may use other numbers; for instance, some indigenous peoples in Australia's Northern Territory use six seasons.

The seasons are caused ultimately by the fact that the Earth's axis is not perpendicular to its orbital plane; it deviates by an angle of approximately 23.5 degrees of arc. Thus, at any given time during the summer or winter, one part of the planet is more directly exposed to the rays of the Sun (see Fig. 1). This exposure alternates as the Earth revolves in its orbit. At any given time, regardless of season, the northern and southern hemispheres experience opposite seasons (see Fig. 2 and Seasonality table).

In most parts of the world, seasons are marked by changes in the amount of sunlight, which in turn often cause cycles of dormancy in plants and hibernation in animals. In the tropics, there is no noticeable change in the amount of sunlight, but there are still fluctuations in rainfall, producing a similar alternation between fertile and infertile times of the year. The concept of seasonality originated from these changes long before its celestial cause became known. These fluctuations are more pronounced at higher latitudes. The Equator does not have any noticeable fluctuation at all. The North Pole and South Pole have extreme fluctuations. There, the sun rises once in the spring and sets once in the fall; thus, the day and night last uninterrupted for 183 calendar days each. Seasonal weather fluctuations also depend on factors such as proximity to oceans or other large bodies of water, currents in those oceans, El Niño/ENSO and other oceanic cycles, and prevailing winds.

The cycle of seasons in the polar and temperate zones of one hemisphere is opposite to that in the other. Thus, when it is day in the North Pole it is night in the South pole and vice-versa. Moreover, when it is summer in the Northern hemisphere, it is winter in the Southern hemisphere, and vice versa, and when it is spring in the Northern hemisphere it is autumn in the Southern hemisphere, and vice versa.

The date at which each season begins depends on whether how it is defined. Astronomically, summer begins at summer solstice, winter at winter solstice, spring at the vernal equinox and autumn at the autumnal equinox.
In the Chinese calendar, the seasons are defined so that the solstice or equinox, occurs in the Middle of the season.

Seasonality table
Northern Hemisphere alternate	Northern Hemisphere alternate	Month	Southern Hemisphere alternate	Southern Hemisphere alternate
Winter	Winter	January	Summer	Summer
Winter		February	Summer
Spring		March	Autumn
	Spring	April		Autumn
		May
Summer		June	Winter
	Summer	July		Winter
		August
Autumn		September	Spring
	Autumn	October		Spring
		November
Winter		December	Summer

@@ Line 1: / Line 1: @@
 [[de:Jahreszeiten]][[nl:seizoen]]
-Earth's [[year]] is traditionally divided into '''seasons''', which are distinguished by changes in the weather and vegetation. The seasonality of a location is determined by a number of factors, including: the inclination of [[Earth]]'s [[axial tilt]] with [[respect]] to the [[orbital plane]], proximity to [[ocean]]s, and the [[Coriolis effect]]. The seasons are not substantially affected by changes in Earth's distance from [[Sol]], which do occur annually.
+<table align="right" border="1" cellpadding="5" width="372">
-The angle with which the sun's rays impact the surface of the earth varies with the position of the earth in its orbit. If the angle is steep the rays will reach the surface close together and lose little energy in the atmosphere.
+<tr><td>'''Fig. 1'''<br>
-If the angle is not steep the rays will be spread out on the surface
+[[Image:seasons.png|A diagram of the seasons]]<br>
-and may lose more energy by passing through the atmosphere longer distances.  Consequently, polar regions are marked by two seasons (day and night); temperate regions are marked by four seasons ([[summer]], [[autumn]], [[winter]], [[spring]]); and tropical regions are often marked by two seasons ([[rainy season|wet]] and [[dry season|dry]]).  In some climates and latitudes people make further distinctions between seasons (e.g. some Indigeneous groups in the Northern Territory of Australia divide the year into six seasons).
+This is a diagram of the seasons.  Note that, however the Earth turns, the [[north pole]] will be dark, and the [[South Pole]] will be illuminated; see also [[arctic winter]].  In addition to the density of the rays, the [[dissipation]] of light in the [[atmosphere]] is greater when it comes in at a shallow angle.</td></tr>
+<tr><td>'''Fig. 2'''<br>
+[[Image:seasons2.png|Another diagram of the seasons]]<br>
+As the Earth revolves around the Sun, seasons alternate in the northern and southern hemispheres.</td></tr></table>
+A '''season''' is one of the major divisions of the [[year]].  Typically, the year is divided into four seasons: ''[[spring]]'', ''[[summer]]'', ''[[autumn]]'' (''fall''), and ''[[winter]]''.  Some cultures may use other numbers; for instance, some indigenous peoples in Australia's [[Northern Territory]] use six seasons.
+The seasons are caused ultimately by the fact that the [[Earth]]'s [[axis]] is not perpendicular to its [[orbital plane]]; it deviates by an angle of approximately 23.5 [[degree]]s of arc.  Thus, at any given time during the summer or winter, one part of the planet is more directly exposed to the rays of the [[Sun]] (see ''Fig. 1'').  This exposure alternates as the Earth revolves in its orbit.  At any given time, regardless of season, the [[northern hemisphere|northern]] and [[southern hemisphere]]s experience opposite seasons (see ''Fig. 2'' and ''Seasonality table'').
+In most parts of the world, seasons are marked by changes in the amount of [[sunlight]], which in turn often cause cycles of [[dormancy]] in [[plant]]s and [[hibernation]] in [[animal]]s.  In the [[tropic]]s, there is no noticeable change in the amount of sunlight, but there are still fluctuations in [[rain]]fall, producing a similar alternation between fertile and infertile times of the year.   The concept of seasonality originated from these changes long before its celestial cause became known.  These fluctuations are more pronounced at higher latitudes.  The [[Equator]] does not have any noticeable fluctuation at all.  The [[Geographic North Pole|North Pole]]  and [[South Pole]] have extreme fluctuations.  There, the sun rises once in the spring and sets once in the fall; thus, the day and night last uninterrupted for 183 calendar days each.  Seasonal weather fluctuations also depend on factors such as proximity to [[ocean]]s or other large bodies of [[water]], [[ocean current|current]]s in those oceans, [[El Ni&ntilde;o]]/ENSO and other oceanic cycles, and prevailing [[wind]]s.
 The cycle of seasons in the polar and temperate zones of one hemisphere is opposite to that in the other. Thus, when it is day in the North Pole it is night in the South pole and vice-versa.  Moreover, when it is summer in the [[Northern hemisphere]], it is winter in the [[Southern hemisphere]], and vice versa, and when it is spring in the Northern hemisphere it is autumn in the Southern hemisphere, and vice versa.
-The date at which each season begins depends on whether how it is defined. Astronomically, summer begins at [[summer solstice]], winter at [[winter solstice]], spring at the [[spring equinox|vernal equinox]] and autumn at the [[autumn equinox|autumnal equinox]].
+The date at which each season begins depends on whether how it is defined. Astronomically, summer begins at [[summer solstice]], winter at [[winter solstice]], spring at the [[spring equinox|vernal equinox]] and autumn at the [[autumn equinox|autumnal equinox]].<br>
 In the [[Chinese calendar]], the seasons are defined so that the solstice or equinox, occurs in the Middle of the season.
-Also, sometimes the seasons are defined as follows:
+<table border="1"><tr><th colspan="5"><font size="+1">Seasonality table</font></th></td>
-*December, January, Feburary are southern hemisphere summer and northern hemisphere winter;
+<tr><th>Northern<br> Hemisphere<br> alternate</th><th>Northern<br> Hemisphere<br> alternate</th><th>Month</th><th>Southern<br> Hemisphere<br> alternate</th><th>Southern<br> Hemisphere<br> alternate</th></tr>
-*March, April, May are southern hemisphere autumn and northern hemisphere spring;
+<tr><td rowspan="2" valign="bottom">Winter</td><td rowspan="3" valign="middle">Winter</td><th>January</th><td rowspan="2" valign="bottom">Summer</td><td rowspan="3" valign="middle">Summer</td></tr>
-*June, July, August are southern hemisphere winter and northern hemisphere summer; and
+<tr><th>February</th></tr>
-*September, October and November are southern hemisphere spring and northern hemisphere autumn.
+<tr><td rowspan="3" valign="middle">Spring</td><th>March</th><td rowspan="3" valign="middle">Autumn</td></tr>
+<tr><td rowspan="3" valign="top">Spring</td><th>April</th><td valign="top" rowspan="3">Autumn</td></tr>
+<tr><th>May</th></tr>
+<tr><td rowspan="3" valign="middle">Summer</td><th>June</th><td rowspan="3" valign="middle">Winter</td></tr>
+<tr><td rowspan="3" valign="top">Summer</td><th>July</th><td rowspan="3" valign="top">Winter</td></tr>
+<tr><th>August</th></tr>
+<tr><td rowspan="3" valign="middle">Autumn</td><th>September</th><td  rowspan="3" valign="middle">Spring</td></tr>
+<tr><td rowspan="3" valign="top">Autumn</td><th>October</th><td  rowspan="3" valign="top">Spring</td></tr>
+<tr><th>November</th></tr>
+<tr><td>Winter</td><th>December</th><td>Summer</td></tr></table>