The Dragonfly Beach Ultimate Tanning and Sunburn Guide
(also good for anywhere else in the world!)
(Assuming clear skies, normal ozone levels, low elevation and no snow or water reflection)
This is a custom program written by the owner of Dragonfly Beach
and to the best of his knowledge, is the only program like it in the world.
Month Day Year Longitude Latitude Time Offset


The pre-filled longitude and latitude are for downtown Brillion. (Can't let the uninvited people find Dragonfly Beach!) Feel free to change the dates, longitude and latitude and re-calculate. To find your own longitude and latitude, go to Google and in the search field, enter the name of your town, state or country and hit enter. You will most likely find the values for your location. Remember, west Longitude is negative and south latitude is negative.

The time offset is from Greenwich (Zulu) Time and is pre-filled for U.S. Central Time Zone (daylight saving times adjusted). If you wish to change the time offset, please calculate your own offset depending on your time zone.
Sun Rise Sun Set
6:53 AM 4:21 PM

Time Degrees above Horizon UV Index Risk Burn Time
7:00 AM00Low>60 Minutes
7:30 AM50Low>60 Minutes
8:00 AM90Low>60 Minutes
8:30 AM130Low>60 Minutes
9:00 AM170Low>60 Minutes
9:30 AM200Low>60 Minutes
10:00 AM221Low>60 Minutes
10:30 AM241Low>60 Minutes
11:00 AM251Low>60 Minutes
11:30 AM261Low>60 Minutes
12:00 PM261Low>60 Minutes
12:30 PM251Low>60 Minutes
1:00 PM231Low>60 Minutes
1:30 PM211Low>60 Minutes
2:00 PM180Low>60 Minutes
2:30 PM140Low>60 Minutes
3:00 PM100Low>60 Minutes
3:30 PM60Low>60 Minutes
4:00 PM20Low>60 Minutes
Click on NOAA UV Index to see today's real UV index for solar noon and local weather conditions.

(The following was copied and modified from Wikipedia Thank you Wikipedia!
UV Index Description Recommended Protection
0–2 Low danger to the average person Wear sunglasses; use sunscreen if there is snow on the ground, which reflects UV radiation, or if you have particularly fair skin.
3–5 Moderate risk of harm from unprotected sun exposure Wear sunglasses and use sunscreen, cover the body with clothing and a hat, and seek shade around midday when the sun is most intense.
6–7 High risk of harm from unprotected sun exposure Wear sunglasses and use sunscreen having SPF 15 or higher, cover the body with sun protective clothing and a wide-brim hat, and reduce time in the sun from two hours before to three hours after solar noon (roughly 11:00 to 16:00 during summer in zones that observe daylight saving time).
8–10 Very high risk of harm from unprotected sun exposure Same precautions as above, but take extra care — unprotected skin can burn quickly.
11+ Extreme risk of harm from unprotected sun exposure Take all precautions, including: wear sunglasses and use sunscreen, cover the body with a long-sleeve shirt and pants, wear a broad hat, and avoid the sun from two hours before to three hours after solar noon.


Acknowledgements, disclosures and disclaimers:
This is the FIRST PHP program I have ever written. I only started researching PHP 3 days before I finished this program.
Thanks to Peter Duffett-Smith who wrote Practical Astronomy with your Calculator 2nd Edition 1985
I used this book to create all of the astronomical functions.
After much searching, I found this page at http://sedac.ciesin.org/ozone/rtm/mval.html. I used the chart to create the UV values for the different sun angles. Thanks to Dr. Sasha Madronich for creating the model.

I used the following programming platforms: Eclipse 3.2.2, PHP 4.4.6-Win 32, Apache 2.2.4 Win 32, PHP Eclipse 1.1.7
(I've tried using DBG 2.13.1, but can't get it configured right. If you have clues for DBG, email me at dfbeach@gmail.com Thanks!)

The PHP files I created are open source. Go to http://www.dragonflybeach.com/astro/ if you want to download them. Comments welcome!

Back to the Dragonfly Home Page