Four Seasons

1. SOLSTICE AND EQUINOX

2. Equinox
 An astronomical event that happens twice, once in spring
and once in autumn each year when the tilt of the Earth's
axis is inclined neither away from nor towards the Sun
 During Equinoxes the tilt of the Earth (with respect to the
Sun) is 0° and because of it duration of the day and the
night are almost equal on Equinox day i.e. 12 hours
 Equinoxes occur on 20th or 21st March and 22nd or
23rd September each year and both days has equal length of
the day and the night.

3. Solstice - solstitium meaning “sun stopping”
 an astronomical event that happens twice, once in summer and
once in winter, each year when the Sun reaches its highest
position in the sky as seen from the North or South Pole
 During Solstices the tilt of the axis of the Earth (with respect to
the Sun) is the maximum at 23° 26'.
 Solstices are preferably referred as June Solstice (Northern
Solstice) and December Solstice (Southern Solstice)
 Solstices occur on 20th or 21st June and 21st or 22nd December each year.
During summer the day of the solstice is the longest day of the year and
during winter the day of the solstice is the shortest day of the year

6.  The first day of the Season of
Summer (JUNE 21)
 hours of daylight are increased
 in the northern hemisphere, the Sun
is farthest north and the length of
time between Sunrise and Sunset is
the longest of the year
The sun rises to the north of east, sets
to the north of west
 the sun is visible in the sky for a longer
period
SUMMER SOLSTICE
It's also known as the northern solstice because it occurs when the sun is
directly over the Tropic of Cancer in the Northern Hemisphere

7. during June Solstice it is summer time in
the UK, the USA, Canada, Russia, India
and China and it is the longest day of the
year while it is winter time in Australia,
Argentina, Chile, New Zealand and South
Africa and it is the shortest day of the year

8. Midnight Sun or Polar Night?
On the June solstice, the midnight sun is visible
(weather permitting) throughout the night, in all areas
from just south of the Arctic Circle to the North Pole.
Sunrise and Sunset Times
On the other side of the planet, south of the Antarctic
Circle there's Polar Night, meaning no Sunlight at all,
on the June Solstice

9. Solstice Dates Vary
 it can happen anytime between June 20 and June 22, depending on which time
zone you're in
 June 22 Solstices are rare - the last June 22 Solstice took place in 1975 and
there won't be another one until 2203
 The varying dates of the solstice are mainly due to the calendar system – most
western countries use the Gregorian calendar which has 365 days in a normal
year and 366 days in a Leap Year
 A tropical year, the time it takes the Earth to orbit the Sun completely, is ca.
365.242199 days, but varies slightly from year to year because of the
influence of other planets. The exact orbital and daily rotational motion of the
Earth, such as the “wobble” in the Earth's axis (precession of the equinoxes),
also contributes to the changing solstice dates

10. WINTER SOLSTICE
 The first day of the Season of
Winter
 DECEMBER 21
 in the northern hemisphere,
the Sun is farthest south and
the length of time between
Sunrise and Sunset is the
shortest of the year
 hours of daylight are decreased
 during December Solstice, it is
winter time in the UK, the USA,
Canada, Russia, India and China
and it is the shortest day of the
year while it is summer time in
Australia, Argentina, Chile, New
Zealand and South Africa and it is
the longest day of the year

11. VERNAL EQUINOX
 The first day of the Season of Spring - and the beginning of a long
period of sunlight at the Pole
 In the northern hemisphere: MARCH 20 (the Sun crosses the Equator
moving northward)
 In the southern hemisphere: SEPTEMBER 22 (the Sun crosses the
Equator moving southward).

12.  On March Equinox, it is spring time in
the UK, the USA, Canada, Russia,
India and China while it is autumn
time in Australia, Argentina, Chile,
New Zealand and South Africa

13. AUTUMN EQUINOX
 The first day of the Season of Autumn - and the beginning of a long
period of darkness at the Pole.
 In the northern hemisphere: SEPTEMBER 22 (the Sun crosses the
Equator moving southward)
 In the southern hemisphere: MARCH 20 (the Sun crosses the Equator
moving northward).

14.  Earth does not move at a constant speed in its elliptical orbit.
Therefore the seasons are not of equal length: the times taken for the
sun to move from the March Equinox to the June Solstice, to the
September equinox, to the December solstice, and back to the March
equinox are roughly 92.8, 93.6, 89.8 and 89.0 days respectively
 The consolation in the Northern Hemisphere is that spring and
summer last longer than autumn and winter

15.  After the June solstice, the sun follows a lower and lower path
through the sky each day in the Northern Hemisphere until it
reaches the point where the length of daylight is about 12 hours
and eight to nine minutes in areas that are about 30 degrees
north or south of the equator
 Areas 60 degrees north or south of the equator have daylight for
about 12 hours and 16 minutes. This is the September Equinox,
the Autumnal Equinox in the Northern Hemisphere
 on September Equinox it is autumn time in the UK, the USA,
Canada, Russia, India and China while it is spring time in
Australia, Argentina, Chile, New Zealand and South Africa

16. on September Equinox, it is autumn time in
the UK, the USA, Canada, Russia, India and
China while it is spring time in Australia,
Argentina, Chile, New Zealand and South
Africa