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I have heard this one from being child (like my mom telling me to be careful) that one gets more sunburn when near the sea/lake as compared to just being outside.

One source claiming this is webmd.com, also this is a 'common knowledge' in Lithuania, and Australia.

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    If you can find examples of this to establish notability, I think this would be a good question. Otherwise, it may be closed as not notable and off-topic.
    – Reinstate Monica -- notmaynard
    Aug 30, 2016 at 14:57
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    Being near any larger reflective surface, e.g. water or snow, will intensify the amount of sunlight your skin is exposed to.
    – Tor-Einar Jarnbjo
    Aug 30, 2016 at 17:00
  • I'm not sure if it's notable enough, and if so, whether this counts as claim or support for it, but WebMd says that being near reflective surfaces including water can cause sunburns by reflection.
    – ReasonablySkeptical
    Aug 30, 2016 at 18:25
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    I confirm that this is a common warning I have heard in Australia. (Similar warning on snow.) So, I think it is notable. A specific cite would improve the question, but I don't think it should be closed.
    – Oddthinking ♦
    Aug 30, 2016 at 23:13
  • Please define near as an actual distance (range)
    – user22865
    Aug 31, 2016 at 9:11

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No not at all. Being near-water decreases the chance of sunburn! From a light or UV scenario the claim is false and the NHS is incorrect. Now snow and white concrete are true.

A common misunderstanding I'm afraid Rory. Water is not reflective. Being near a sea or Lake as you state would actually be better than just being outside (Figure 2), all other things being equal.

Water absorbs (https://www.esr.org/outreach/glossary/albedo.html) it does not reflect. You really need to look at UV though.

Figure 1

Here are the rates. Check out water. Virtually 0 reflection!

Figure 2

and here are your sources.

Sample albedos

Surface Typical

albedo

Fresh asphalt 0.04 Pon, Brian (30 June 1999). "Pavement Albedo". Heat Island Group. Archived from the original on 29 August 2007. Retrieved 27 August 2007

Open ocean 0.06 "Thermodynamics | Thermodynamics: Albedo | National Snow and Ice Data Center". nsidc.org. Retrieved 2016-08-14.

Worn asphalt 0.12 Pon, Brian (30 June 1999). "Pavement Albedo". Heat Island Group. Archived from the original on 29 August 2007. Retrieved 27 August 2007

Conifer forest (Summer) 0.08,[4] Alan K. Betts; John H. Ball (1997). "Albedo over the boreal forest". Journal of Geophysical Research. 102 (D24): 28,901–28,910.

(overall) 0.09 to 0.15 "The Climate System". Manchester Metropolitan University. Retrieved 11 November 2007

Deciduous trees 0.15 to 0.18 "The Climate System". Manchester Metropolitan University. Retrieved 11 November 2007

Bare soil 0.17 Tom Markvart; Luis CastaŁżer (2003). Practical Handbook of Photovoltaics: Fundamentals and Applications. Elsevier. ISBN 1-85617-390-9.

Green grass 0.25 Tom Markvart; Luis CastaŁżer (2003). Practical Handbook of Photovoltaics: Fundamentals and Applications. Elsevier. ISBN 1-85617-390-9.

Desert sand 0.40 Tetzlaff, G. (1983). Albedo of the Sahara. Cologne University Satellite Measurement of Radiation Budget Parameters. pp. 60–63.

New concrete 0.55 Tom Markvart; Luis CastaŁżer (2003). Practical Handbook of Photovoltaics: Fundamentals and Applications. Elsevier. ISBN 1-85617-390-9.

Ocean ice 0.5–0.7 Tom Markvart; Luis CastaŁżer (2003). Practical Handbook of Photovoltaics: Fundamentals and Applications. Elsevier. ISBN 1-85617-390-9.

Fresh snow 0.80–0.90 Tom Markvart; Luis CastaŁżer (2003). Practical Handbook of Photovoltaics: Fundamentals and Applications. Elsevier. ISBN 1-85617-390-9.

By far the best question you can ask is does UV reflect from water as this is what mostly causes burn. UV is somewhat different than visible light (Figure 3). If you are swimming in the top meter of water you will be exposed to 90% of the UV but out the water this would be 100% and next to the water it would be close to zero, if not zero from the UV hitting the water.

Figure 3

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    I think you are misrepresenting the data here. It is a given that some UV is reflected (the data from the sites you link to confirms this) - ergo an individual on a boat, for example, will experience UV from above, and reflected from the water - which increases the total UV exposure. Yes, the problem is much worse for snow, but it is still a problem on water, as any sailor will tell you!
    – Rory Alsop
    Aug 31, 2016 at 10:34
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    @Rory Aslop. It's relative right? Has to be compared to other surfaces you are around and water had much lower reflectance. The question asks about (most likely kids) about being near sea or water. If about being on a boat my answer would be a little different. By the way most of the issue from a boat is also misunderstood. It is reflection from the often white boat and not the water combined with a lack of shade relative to land. Asking fisherman is not really scientific and the boat thing is also a misconception. Again it is not the water but the boat and lack of shade. Water absorbs more.
    – If you do not know- just GIS
    Aug 31, 2016 at 14:03
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    Water not reflecting would not "decrease" because it wouldn't somehow leech off the direct sunlight hitting a person. It would, very, very slightly (probably not enough to deem the claim "true") increase the exposure because it does reflect a small amount of UVA. However, the much greater increase would come from the UV light reflected from the sand that is present near many water recreation sights (beaches).
    – PoloHoleSet
    Sep 21, 2016 at 22:54
  • @Ifyoudonotknow-justGIS Hi, I would appreciate if you could add that it is likely that sand on the beach is what is adding to sunburn (rather than water). As your answer might be misinterpreted... And thanks for the answer.
    – Matas Vaitkevicius
    Sep 26, 2016 at 8:20
  • Yes sand would increase it. So would the fact you have less relative shade. So would the fact you tend to be closer to nude. So would the fact you tend to be out in the sun longer. The water is one off your lesser concerns. It is just that all above tend to happen closer to water but again it is not the water per se.
    – If you do not know- just GIS
    Sep 28, 2016 at 3:00
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Yes.

From the UK's National Health Service:

Snow, sand, concrete and water can reflect the sun’s rays onto your skin, and the sun is more intense at high altitudes.

and as CPerkins commented, WebMD:

Whether you are near reflective surfaces, such as water, white sand, concrete, snow, and ice.

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  • For a more theoretical understanding, this paper measures the albedo of water for Ultraviolet and compares it to grass. You can see how much more UV is reflected back up (where, from experience, it can hit the paler parts of your skin.)
    – Oddthinking ♦
    Aug 30, 2016 at 23:25
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    @Oddthinking The paper shows the opposite of what you state. See figure 4 and 5. Water is only <0.06 and <0.08. Just as in my answer Figure 2 (about 8%). I am confused why this is causing confusion. Yeah maybe a (2-3%) tiny bit more than grass but way less than concrete, sand, etc., indeed as much as 40 - 50% less.
    – If you do not know- just GIS
    Aug 30, 2016 at 23:41
  • Thanks for your comment. I've no doubt that sand and snow are far worse. I was comparing it to grass, for which water is it much more reflective. But you made me reexamine the absolute figures, and you are right - they are smaller than I thought. I think I misread the position of the decimal places in Table 1, making me overestimate its importance. Sorry.
    – Oddthinking ♦
    Aug 31, 2016 at 0:26
  • "near reflective surfaces, such as water," WedMB and NHS are hardly strong sites for what is a physics question. Water is not a reflective surface. The ocean absorbs much (90%) of the energy that hits it and the earth's land masses have varying levels of albedo depending on the geography and such.
    – If you do not know- just GIS
    Sep 3, 2016 at 15:41

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