why does water feel colder than air
On April 21, Her Majesty Queen Elizabeth II will turn 92 years old. To mark, there are usually a series of gun salutes around London: a 41 gun salute in Hyde Park, a 21 gun salute in Windsor Great Park, and a 62 gun salute at the Tower of London. For the most part, the monarch celebrates her big day privately. But onPJune 9, 2018, Her Majesty will parade throughPLondon as part of an opulent birthday celebration known as. Queen Elizabeth, like many British monarchs before her, has two birthdays: the actual anniversary of the day she was born, and a separate day that is labeled her "official" birthday (usually the second Saturday in June). Why? Because April 21 is usually too cold for a proper parade. The tradition in 1748, with King George II, who had the misfortune of being born in chilly November. Rather than have his subjects risk catching colds, he combined his birthday celebration with the Trooping the Colour. The parade itself had been part of British culture for almost a century by that time. At first it was strictly a military event, at which regiments displayed their flagsor "colours"so that soldiers could familiarize themselves. But George was known as a formidable general after having led troops at the Battle of Dettingen in 1743, so the military celebration seemed a fitting occasion onto which to graft his warm-weather birthday. Edward VII, who also had a November birthday, was the first to standardize the June Trooping the Colour and launched a tradition of a monarchical review of the troops that drew crowds of onlookers.
Even now, the date of the "official" birthday varies year to year. For the first
of her reign, Elizabeth II held her official birthday on a Thursday but has since switched over to Saturdays. And while the date is tied to the Trooping the Colour in the UK, Commonwealth nations around the world have their own criteria, which generally involve recognizing it as a public holiday. Australia started recognizing an official birthday back in 1788, and all the provinces (save one) observe the Queen's Birthday on the second Monday in June, with Western Australia holding its celebrations on the last Monday of September or the first Monday of October. In Canada, the official birthday has been set to align with the actual birth date of Queen VictoriaMay 24, 1819since 1845, and as such they celebrate so-called Victoria Day on May 24 or the Monday before. In New Zealand, it's the first Monday in June, and in the Falkland Islands the actual day of the Queen's birth is celebrated publicly. All in all, just another reason it's great to be Queen. Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at @mentalfloss. com. We're warm blooded so we will always be warmer than the surroundings.
Water sucks heat out of your body faster than air of the same temperature. Water only conducts heat 25 times better than air. However, it can suck heat out of you much more than 25 times faster. Water even feels colder than glass of the same temperature even though it's actually only half as good a heat conducter. Heat conductivity is volumetric heat capacity times thermal diffusivity. For any gas, its thermal diffusitivity is approximately a constant times Kelvin temperature squared divided by pressure divided by molar mass and volumetric heat capacity is approximately another constant times pressure divided by Kelvin temperature divided by molar mass. That means heat conductivity for a given gas remains constant as pressure changes at constant temperature. Since water has a similar molar mass to that of air but conducts heat 25 times better, it can't be treated like a heavily compressed gas. For an infinitely heat conductive object suspended in a stationary fluid in the absense of gravity at a given amount higher temperature than the fluid, its rate of heat loss varies solely as the heat conductivity of the fluid. For any infinitely heat conductive object of a given amount higher temperature than the fluid its in, above a certain speed where heat diffuses a distance equal to its size in the time it takes to move its own length, the thickness of the fluid layer it's losing heat through varies as the inverse square root of its speed so its rate of heat loss varies as the square root of its speed.
Also, given that's it's moving through a fluid then another fluid at the same speed which for both fluids is above the speed that that relationship holds. The thickness of the conducting layer varies as the square root of the thermal diffusivity and is independent of the volumetric heat capacity. That means the rate of heat loss is heat conductivity divided by square root of thermal diffusivity. Since water conducts heat 25 times better then air but also has a lower thermal diffusivity, it sucks heat more than 25 times faster. You don't conduct heat infinitely well but because of circulation, you're pretty close to doing so. That means the rate you lose heat will be the rate you would be predicted to lose heat up to a certain limit above which the rate of cooling of your surface becomes faster than that predicted if you conducted heat infinitely well. When you go into water, the water is moving around you and the rate of cooling predicted if you conducted heat infinitely well indeed is above that limit so your surface cools even faster until it reaches the water's temperature. That's why water sucks heat out of you so much faster than air.
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