Wikipedia:Reference desk/Archives/Science/2021 February 15

= February 15 =

Simple glacier models
Has someone ever made a simple glaciological model that relates insolation, temperature and precipitation (perhaps also wind) with the equilibrium line altitude? Perhaps only for a simple conical mountain. Jo-Jo Eumerus (talk) 15:24, 15 February 2021 (UTC)
 * GScholar for "snow line modelling" turns up Multi-decadal mass balance series of three Kyrgyz glaciers..., Barandun et al. 2018. §3.6 seems like a good starting point and has some cites to a "classical temperature-index melt model". Tigraan Click here to contact me 16:58, 15 February 2021 (UTC)
 * Thing is, none of that discusses an ELA from a quick check. I should probably specify that I have seasonal freezing level elevation, insolation and precipitation. Jo-Jo Eumerus (talk) 13:48, 16 February 2021 (UTC)

Meteors approaching head-on
Are there any observations of individual meteors, bolides, etc flying head-on (that is, towards the observer on an approaching course in the atmosphere) rather than parallel to the observer? 212.180.235.46 (talk) 22:24, 15 February 2021 (UTC)
 * There are a gazillion videos of the Chelyabinsk meteor. I'd look there. I doubt you're going to find an exact Hollywood-style "ahh it's coming right for us" video, just because it would be such a freak occurence. --47.152.93.24 (talk) 02:36, 16 February 2021 (UTC)


 * In the 2001 film adaptation of The Discovery of Heaven, such an event is shown from the subjective viewpoint of a protagonist, but as they were instantly vaporized and could not leave a record, the event as shown through the eyes of an imminently moribund character can equally be described as being from an omniscient point of view.


 * [Not the previous unsigned commenter] Various textbooks, etc., discussing meteor observation that I have read over the last 50-odd years have mentioned that such 'head-on' meteors are occasionally both observed visually and recorded photographically. Usually they are seen at the radiant point of a meteor shower being observed/photographed: the chances of seeing a non-shower sporadic meteor head on are obviously much more slim, although I might have seen one in late 1985 (within the Square of Pegasus) while looking for Halley's comet at dusk.
 * A meteor is of course an atmospheric phenomenon usually occurring at an altitude of some 80 miles or so. Only if the meteoroid that causes it were to be unusually large and reach the ground as a meteorite or explode at a low altitude as a bolide could it harm a 'head-on' observer. {The poster formerly known as 87.81.230.195} 2.125.74.203 (talk) 13:26, 16 February 2021 (UTC)

Why is electrolysis more effective at permanent hair removal than laser hair removal is?
Why is electrolysis more effective at permanent hair removal than laser hair removal is? Futurist110 (talk) 22:58, 15 February 2021 (UTC)
 * Who says it is? ←Baseball Bugs What's up, Doc? carrots→ 23:02, 15 February 2021 (UTC)
 * https://www.allclearelectrolysis.com/faqs "Laser is permanent hair reduction while electrolysis is permanent hair removal as approved by FDA." Futurist110 (talk) 23:22, 15 February 2021 (UTC)
 * Consider the source. Of course a site promoting electrolysis will using wording to promote it. Do you have any neutral sources that say one is better than the other?  RudolfRed (talk) 00:35, 16 February 2021 (UTC)
 * This link talks about the FDA approving laser hair removal for permanent hair reduction, but NOT for permanent hair removal: https://web.archive.org/web/20180725213940/https://www.fda.gov/radiation-emittingproducts/resourcesforyouradiationemittingproducts/ucm252757.htm Futurist110 (talk) 01:03, 16 February 2021 (UTC)
 * Efficacy of laser treatment actually depends on the type of hair you have and your skin phototype. Electrolysis works by sending a current through a needle to cauterize each hair follicle one by one. Laser treatment works by pulsing beams at wavelengths absorbed by dark hair follicles; the absorbed energy is converted to heat which destroys the follicle. Blond and red chromophores are not targeted effectively by lasers because there is less absorption at the wavelengths needed to zap the follicles. Laser are also not generally appropriate for people with dark skin as they have to use lower laser fluences to protect against burning the more-pigmented epidermis. The best candidate for effective laser treatment has pale skin and dark hair. JoelleJay (talk) 03:03, 16 February 2021 (UTC)