The Earth revolves around the sun over the course of 365.25 days. As it orbits the sun, different parts of the Earth experience different seasons due to changes in the amount of direct sunlight. On June 21st in the Southern Hemisphere, it is the winter solstice, meaning they have their longest night and shortest day of the year.

1. REVOLUTION AROUND THE SUN

2.  The Earth revolves around the sun.
 One revolution takes 365 ¼ days (one year)
to be completed.
 The path the Earth travels is called an orbit.

4.  At each position in the orbit people in
different parts of the world experience
different seasons.
 In the Southern hemisphere, midsummer’s
day falls on 21 December called the
summer solstice.
 During the summer solstice we have long
days and short nights and receive the
most insolation. We have the longest day
and the shortest night.

6.  Between December and march we move
from summer to autumn and days become
shorter.
 SH Mid-autumn day falls on 21 March –
called autumn equinox and the days and
nights are at equal lengths.

7.  Between March and June we move from
autumn to winter - days become more
shorter -less insolation.
 SH Mid-winter day fall on 21 June, this is
called winter solstice. We then have the
longest night and the shortest day.

8.  Lastly, between June and September we
move from winter to spring.
 SH Mid-spring day falls on 23rd September
called-the spring equinox and the day and
night are of equal length.

9. ACTIVITY
(Using image on next slide)
1. Which season is the southern hemisphere
experiencing?
2. How does the diagram show this?
3. Which part of the Earth’s surface has 24
hours of daylight?
4. Which date in the year does this diagram
represent?
5. Name the two factors that cause the Earth
to have seasons.