Solar Noon
What is solar noon?
Solar noon is the point in the
day that divides the
daylight hours exactly in
half.
It always occurs half-way
between local sunrise and
sunset times.
What is solar noon?
It is the time when the sun
reaches its highest point in
the sky.
It is sometimes referred to
as local apparent noon.
Is solar noon the same
as clock noon?
Clock noon is the midpoint of a
24 hour day. It is12:00p.m.,
or 12 o’clock noon as
measured by a clock or watch.
The Earth is divided into Time
Zones. These regions are very
wide and cover hundreds of
miles.
Is solar noon the same
as clock noon?
Consider this:
in Bowling
Green,
•You
At are
12:00p.m.
(clock
noon),Kentucky
you both and
look your
up
at
thefriend
sun. is in Amarillo, Texas.
best
• Will
sunare
be in
in the
the Central
same position
over
head
Boththe
cities
time zone
but
are
for
each
of you?
1,000
miles
apart.
Clock noon for both of
these cities is12:00p.m.
Solar noon for Bowling Green is 17:40 UTC
and for Amarillo is 19:02 UTC.
(calculated on Dec.14, 2010 for Dec.14, 2010)
Why Solar Noon Varies
Because solar noon is based on the
position of the sun in sky, there are
many factors that affect it and cause
it to change daily.
Why Solar Noon Varies
1. The primary
factor is the
longitude of the
location. Only
one longitude
can experience
solar noon at
any moment.
Why Solar Noon Varies
2. The movement of the earth in
relationship to the sun also affects
solar noon.
– Elliptical orbit
– Solar angle (Earth’s tilt)
Why Solar Noon Varies
Analemma
Athens, Greece
Jan. 4, - Dec. 20,
2004
Why Solar Noon Varies
• Earth’s tilt and revolution around the
sun cause a steady change in the
striking angle of the sun
Solar Noon
Summary
• Midpoint of daylight hours –
halfway between sunrise & sunset
• Changes day to day due to
• Geographic location on the Earth
• Earth-Sun revolution
• Earth’s tilted axis