Investigating How Solar Energy Depends on Latitude
(distance
from the
equator)
This graph shows the amount of energy that comes from the sun during a 24-hour period.
- When it is straight up, it sends a lot of energy to each square foot of ground.
- When the sun is low near the horizon, each square foot of ground gets less energy.
- When the sun is below the horizon, it obviously can‛t supply any energy to the ground!
The horizontal line at the bottom of the graph is the hour line. It goes from midnight (M)
to noon and then to midnight again. You can decide how long the sun is above the horizon
by comparing sunrise and sunset with the lines that mark 6 am, noon, and 6 pm.
a
lot
Amount
of
Solar
Energy
zero
M
6 am
noon
6 pm
M
1. Put at dot on the hour line at 9 o‛clock in the morning.
2. About what time did the sun rise on this day? ______________
3. About what time did the sun set? ________________
4. About how many hours of sunlight did this place get on this day? ____________
5. About what hour of the day was the sun highest in the sky? _____________
6. About what two times of the day was the energy from the sun about half as much
as it was at noon? ________________ ________________
7. Do you think this graph shows a day in summer or winter? ________________
8. Draw a line on the graph to show what you think the sunshine graph would look like
in another season of the year. Write the season name on your line.
©2012 P Gersmehl Teachers may copy for use in their classrooms. Contact [email protected] regarding permission for any other use.
Investigating Latitude and Solar Energy
Take a globe and shine a bright light on it from one side.
The light hits exactly half of the globe; the other half is in darkness.
This simple picture is complicated by the fact that the earth does not stand “straight up.”
It tilts at a constant angle as it moves around the sun. This is the reason for seasons.
Rules for March 21 and September 21.
The sun shines directly down on the equator. People there see it directly overhead at noon.
People anywhere else see the noon sun at an angle “down” from overhead.
That angle is exactly equal to their latitude. (At the poles, the sun is on the horizon.)
Daylight is exactly 12 hours long at every place on earth (except the poles, where there is
24 hours of sunrise/sunset!)
Rules for June 21:
The sun shines directly down on the Tropic of Cancer (23oN).
People anywhere else see the sun at an angle “down” from overhead (if they see it at all).
The number of hours of daylight varies from 24 north of the Arctic Circle (66oN)
to 12 at the equator and zero south of the Antarctic Circle (66oS).
Rules for December 21.
The sun shines directly down on the Tropic of Capricorn (23oS).
People anywhere else see the sun at an angle “down” from overhead (if they see it at all).
The number of hours of daylight varies from zero north of the Arctic Circle (66oN)
to 12 at the equator and 24 south of the Antarctic Circle (66oS).
You can memorize rules and write them back on a test, but to prove you really understand
what they mean, you should be able to match graphs of sunshine with places and dates.
Write the number of the graph that shows
the sunshine that hits the ground on that day
at each of these major world cities:
1
2
3
4
5
6
7
8
9
___ A. Clear March day in Singapore (1oN)
___ B. Clear March day in Delhi (29oN)
___ C. Clear March day in Moscow (56oN)
___ B. Clear June day in Delhi (29oN)
___ E. Clear June day in Moscow (56oN)
o
___ F. Cloudy June day in Moscow (56 N)
___ G. Cloudy December day in Delhi (29oN)
___ H. Clear December day in Delhi (29oN)
___ I. Clear December day in Moscow (56oN)
6 am noon 6 pm
The line shows how “high” the sun
is above the horizon at each hour
from midnight to midnight each day.
Note the marks at 6 am, noon, and 6 pm.
Thought question: Which place has the best potential for solar electricity all year long?
©2012 P Gersmehl Teachers may copy for use in their classrooms. Contact [email protected] regarding permission for any other use.
Investigating Latitude and Solar Energy
1
2
3
4
5
6
7
8
9
6 am
Write the number of the graph that shows
how much sunshine hits the ground on that day
at each of these major world cities:
___ A. Clear March day in Singapore (1oN)
___ B. Clear March day in Delhi (29oN)
___ C. Clear March day in Moscow (56oN)
noon
6 pm
The line shows how “high” the sun
is above the horizon at each hour
from midnight to midnight each day.
Note the marks at 6 am, noon, and 6 pm.
Thought question 1:
Which place has the best potential
for solar electricity all year long?
Why?
___ B. Clear June day in Delhi (29oN)
___ E. Clear June day in Moscow (56oN)
___ F. Cloudy June day in Moscow (56oN)
Thought question 2:
Which place has the best potential
for crop growth in summer? Why?
___ G. Cloudy December day in Delhi (29oN)
___ H. Clear December day in Delhi (29oN)
___ I. Clear December day in Moscow (56oN)
©2012 P Gersmehl Teachers may copy for use in their classrooms. Contact [email protected] regarding permission for any other use.
Investigating How Solar Energy Depends on Latitude
(distance
from the
equator)
Stand a globe with the north pole up and shine a bright light on it from one side.
The light hits exactly half of the globe. The other half is in darkness.
Rules for 21st of March or September.
The sun at noon is straight up at the equator.
People in any other city or town see the noon sun at an angle “down” from overhead.
Daylight is 12 hours long in every city and town (it‛s 24 hours of sunrise at the Poles).
Rules for around the 21st of June:
If you are in the southern hemisphere,
If you are in the northern hemisphere,
1) the sun at noon is lower in the sky
1) the sun at noon is higher in the sky
than it is in spring or fall,
than it is in spring or fall,
2) the number of hours of daylight
2) the number of hours of daylight
is less than 12, and
is more than 12, and
3) daylight gets shorter as you go farther
3) daylight gets longer as you go farther
away from the equator - at the Pole,
away from the equator - at the Pole,
each day has 24 hours of darkness.
each day has 24 hours of sunlight.
Rules for around the 21st of December: If you are in the northern hemisphere,
use the summer rule for the southern hemisphere, and vice versa.
These graphs show how “high” the sun is above the horizon as time goes from midnight to noon
and then back to midnight. You can decide if the sun is shining for more or less than 12 hours
by comparing sunrise and sunset with the lines that mark 6 am, noon, and 6 pm.
The graphs come from three places:
- Singapore (right on the equator),
- Delhi (about 1/3 of the distance
from the equator to the North Pole),
- Moscow (about 2/3 of the distance
from the equator to the North Pole).
Write the number of the graph
that shows how much sunshine
hits each of these world cities
on the day indicated:
1
2
3
4
5
6
___ A. March day in Singapore (1oN)
___ B. March day in Moscow (56oN)
___ C. June day in Delhi (29oN)
___ D. June day in Moscow (56oN)
___ E. December day in Delhi (29oN)
___ F. December day in Moscow (56oN)
M
6 am
noon
6 pm
M
©2012 P Gersmehl Teachers may copy for use in their classrooms. Contact [email protected] regarding permission for any other use.