Move the red date indicator to about March 21 and move the observer standing on Earth to
an observer's latitude of about 40°N. Now record the Sun's Altitude on March 21 in Table 2.1
below.
The red line at the observer's latitude can be used to estimate the Hours the Sun is Up by esti-
mating what percentage of the 24-hour day the observer will be in daylight and in darkness as
Earth rotates. Put another way, what fraction of the red line is in daylight and what fraction is
in darkness? Take the daylight fraction and multiply by 24. This gives the estimated number of
hours of daylight for that date and latitude. Estimate the Hours the Sun is Up on March 21 from
40°N and record in Table 2.2 below.
Use the red date indicator and move observer standing on Earth to repeat what you just did for
all four latitudes and all four dates in Table 2.1 and Table 2.2 until all the entries in BOTH
TABLES are filled out.
Date
March 21
TABLE 2.1 Sun's Altitude
June 21
September 21
December 21
Date
March 21
TABLE 2.2 Hours the Sun is Up (0-24)
40°N 70°N 20°N 40'S
40°N 70°N 20°N 40'S
June 21
September 21
December 21
