Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
BTW, what's at the end of the Stainback Hwy, or what's along there
I've never been up there, but I'm told it's pretty remote and little used. At the end of the road is Kilani Correctional Institute, a medium security prison that was closed during budget cutbacks by former Governor Lingle, and is now in the process of being reopened. Also in January a couple of bodies were found dumped along that road, from two separate murders, so I wouldn't recommend it for hikers.
People often don't consider how much closer HI is to the equator than the mainland, so even coming from the South, which is much, much warmer for half the year, they don't understand why they may burn more easily. Heat is not not a realiable way to determine a need for sunscreen.
Also, sunscreen does not block enough "sun" from your body to give you a deficiency and make you sick-that's simply misinformation.
I also feel like the commenter saying all people need to do is "aclimate to the sun for a few days and you'll never get burned" needs to put some breaks on that before people start taking that advice. It's great you have the genetics to not get burned (notice I don't say not damaged, as you can be damaged without burning), but most people do not. You can be of island decent and live there your entire life and be very outdoors oriented and still get burned if you don't watch yourself. This users personal experience surely does not fit the masses and it's dangerous advice.
I've never been up there, but I'm told it's pretty remote and little used. At the end of the road is Kilani Correctional Institute, a medium security prison that was closed during budget cutbacks by former Governor Lingle, and is now in the process of being reopened. Also in January a couple of bodies were found dumped along that road, from two separate murders, so I wouldn't recommend it for hikers.
I saw the buildings on Google maps satellite view and couldn't figure out what they could be. Prison makes sense. Too bad there isn't any hiking around there, but I guess it's just forest, no volcanic cones or other features to make it appealing.
For latitude to make a difference the sun would need to be considered a point source so you could get your angular difference. The rays from the sun come at the same angle for the entire earth. Otherwise the earth wouldn't have a umbra.
Wrong, or rather, your math only makes sense on a flat earth. Yes, we are considering that all sun rays striking the earth have the same angle. But because the earth is a sphere, people at different latitudes are at different angles to the parallel rays of the sun.
Note that people at different longitudes are also at different angles to the sun, and as a result, we have time zones.
Quote:
Originally Posted by Fredesch
Where latitude comes into play is the number of hours of sunlight in a day. On the equator you get 12 hours of sun every day. Above a tropic you get more hours of sunlight in the summer than the winter.
Wrong again. All your statements are factually correct (except it should be "Above the equator, you get more hours of sunlight..."), but the number of hours of sunlight are not the main factor affecting sunburns. In a scientific study, you would control for the time of exposure (as in keep it the same) to isolate the effects of latitude. As the wikipedia article above explains, there are 2 main factors:
- Density of incident light from different angles
- Dissipation of light from travelling through more atmosphere
Of course, altitude also makes a difference, because it affects the amount of dissipation, but we weren't disagreeing on that.
Yes, it has been a long time since I did the math. And what you say might be true. As far as I remember, the earth has a radius of almost 4,000 miles (3959 according to the Wikipedia) and the thickness of the atmosphere is about 30 miles (including the ozone layer). So unless you are above 72 degrees there is not a loss because of the roundness of the earth. My guess is Minnesota doesn't get above 50 degrees. So the loss due to the roundness of the earth, hmm well you figure that out.
And in the summer time, where you are is tilted toward the sun. And we have a thinner ozone layer, even holes at high latitudes, so all that extra help of going though the ozone at an angle is lost. So I don't think Minnesota ends up getting any more protection from the sun than Hawaii. It isn't significant. And please don't bring up that we are farther from the sun during the northern summer... It just doesn't matter.
I found this info from NASA to clear a few things up:
Quote:
The tropics (from 0 to 23.5° latitude) receive about 90% of the energy compared to the equator, the mid-latitudes (45°) roughly 70%, and the Arctic and Antarctic Circles about 40%.
Here's another good piece, focusing on the UV rays... and confirming that the ozone layer is thinner at the equator, and in the tropics, than it is further north.
Good point, interesting that it says ozone is created in the tropics and moves to the mid to higher latitudes. So I guess Hawaii may have more burn power than Minnestoa. Remind me to slather up before visiting an observatory.
I'm no expert but I know what has worked for me and my daughter for many years. Hey at least I try to be careful and take 2-3 days to acclimate compared with others that hit the beach the first day and turn bright lobster red.
My doctor told me about studies showing the overuse of sunscreen and the increase in bone cancers, especially in the young. I've read many articles about it in recent years. Science and medicine is always being refined as more information is discovered.
Sunscreen | Health and Wellness What’s in Your Sunscreen?
Experts say the number of children and adults with low vitamin D levels has sky rocketed due to sunscreen use. And this has caused a huge jump in bone problems and other health issues.14
Sunscreen - Does Sunscreen Really Protect You? Do All Sunscreens Protect Your Skin from Ultraviolet Radiation?
Yet while most sunscreens block out at least some UVB radiation, many don’t screen UVA rays at all, making their use risky. According to the nonprofit Environmental Working Group (EWG), by far most of the commercially available sunscreens do not provide adequate protection against the sun’s harmful UV radiation and may also contain chemicals with questionable safety records.
Sunscreen and vitamin D
The use of sunscreen with a sun protection factor (SPF) of 8 inhibits more than 95% of vitamin D production in the skin.[60][61]
Holick MF (December 2004). "Sunlight and vitamin D for bone health and prevention of autoimmune diseases, cancers, and cardiovascular disease". Am. J. Clin. Nutr. 80 (6 Suppl): 1678S–88S. PMID 15585788.
Sayre, Robert M.; John C. Dowdy (2007). "Darkness at Noon: Sunscreens and Vitamin D3". Photochemistry and Photobiology 83 (2): 459–63. doi:10.1562/2006-06-29-RC-956. PMID 17115796.
A recent study has shown that more Australians and New Zealanders are vitamin D deficient than previously thought.[62] Ironically, there are indications that vitamin D deficiency may lead to skin cancer.[63]
Nowson C, Margerison C (2002). "Vitamin D intake and vitamin D status of Australians". Med J Aust 177 (3): 149–52. PMID 12149085.http://pics3.city-data.com/forum/
Grant WB (2002). "An estimate of premature cancer mortality in the U.S. due to inadequate doses of solar ultraviolet-B radiation". Cancer 94 (6): 1867–75. doi:10.1002/cncr.10427. PMID 11920550
Please register to post and access all features of our very popular forum. It is free and quick. Over $68,000 in prizes has already been given out to active posters on our forum. Additional giveaways are planned.
Detailed information about all U.S. cities, counties, and zip codes on our site: City-data.com.
Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
