Me and My Shadow - Testing a Rule-of-Thumb for Safe Sun Exposure
BACKGROUND
Have you heard the following rule-of-thumb for safe Sun exposure? Is it
true? Let's experiment to discover the answer!
The Sun's rays are strongest between 10 a.m. and 4 p.m. Whenever possible,
limit exposure to the Sun during these hours. An easy way to tell how much
ultraviolet (UV) radiation exposure you are getting is to look for your
shadow:
- If your shadow is taller than you are (in the early morning and late
afternoon), then your UV exposure is likely to be low.
- If your shadow is shorter than you are (around midday), then you are
being exposed to high levels of UV radiation. Seek shade and protect your
skin and eyes.
PROCEDURE
Once an hour, use a meter stick to measure the length of your shadow (or
use the SCSA Shadow Length
Calculator); use a hand-held UV meter to measure the UV Index. Use the
following data table to record the time, your height, your shadow length,
and the UV Index. You may opt to record the Sun's apparent altitude.
Data Table
| Time |
Your Height |
Your Shadow Length |
UV Index |
Sun's Apparent Altitude |
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