Windchill, how does it really work

The original 1941 windchill index calculation, developed by Paul Siple and Charles Passel, was primarily intended to quantify the rate at which water would freeze under varying wind speeds and temperatures. This scientific tool aimed to provide insights into the freezing process and aid in understanding the impact of wind on environmental conditions.
However, over time, misunderstandings have arisen regarding the application of this index. While it was meticulously designed for studying freezing phenomena, it was not originally intended for assessing human thermal comfort or predicting how quickly an individual would cool down in cold weather.
Recognizing the limitations of the original index, significant advancements have been made in the field of thermal comfort assessment. In the year 2000, the Joint Action Group for Temperature Indices introduced a new and improved method for calculating wind chill. This updated approach incorporates modern scientific understanding of human physiology and environmental factors, providing a more accurate representation of how wind and temperature interact to influence perceived coldness and potential heat loss.
Despite the availability of this newer method, it's important to appreciate the historical significance of the original windchill index while also acknowledging the advancements that have been made in the field. Both serve as valuable tools in understanding and mitigating the effects of cold weather on human health and comfort.

[@Seamus3051]

Never stop waffleing, it is wonderfully instructive.🙂 Cheers

[@redf7209]

It can't be underestimated. I was once out in very cold weather and doing fairly well until I helped someone with skis and got some ski wax/lubricant on my hand. After that I lost so much heat via that one hand that I really suffered from that chill.

[@frankcooper6118]

I think the latent heat of evaporation is a factor when it comes to moisture making us feel colder, particularly in combination with wind. It takes energy for water to change from liquid to gas and some of that energy comes from our skin, this is why we produce sweat when we are too warm, the evaporation of sweat cools us down. Wind causes water to evaporate quicker, which is why washing dries quicker on a windy day, all other things being equal.

[@jamesbparkin740]

Yup, which is why hand sanitiser feels even colder than water if you shake your hands around, because the alcohol evaporates more readily than water.

[@jamesbparkin740]

And why your back feels colder than the rest of you in a breeze at the top of a hill on a warm day when you take your rucksack off. After all, the sweat is at body temperature at the start

[@redf7209]

It is illustrated by evaporation of Either that will chill a surface sufficiently for moisture in air to freeze on that surface.

[@andreattazanella]

Another great video! Best explanation on the topic ever!

[@stroppy7]

Hello, Love the channel! A great followup video to this one would be how rainy conditions contribute to heat-loss. I recently went on a multi-day hike on the west coast of Vancouver Island and learnt a lot about damp (high dew point), rain forest, coastal, wet/rainy weather conditions. How do you deal with wetness and rain? Do you have a method to evaluate the chance for hypothermia? I quickly learnt that a puffy jacket is useless and that my synthetic fleece top (packed it as a just-in-case) saved my bum big time. Looking forward to the next video! -Hedvig

[@muddyfox50]

Sorry about the lack of hot, sunny days. We're hogging those in Cambridge. We'd share except they're just so nice.

[@jvpateluk]

I can only speak for myself, but your personal opinion counts for a lot!

[@tomtom4405]

Years ago you had a thing that looked like an old fashioned football rattle (if you know what that is) called a "whirling hygrometer" and you whirled it round and round. It had a wet bulb thermometer and a dry bulb thermometer and a lookup table. With such a simple non digital gadget you can see the temp, relative humidity, how far from the dew point you are (important for spray painting and blast cleaning, to stay inside specs). If you knew windspeed you could also lookup how much wind-chill. So much can be done simply and easily without any electronic gadgets!

[@TheMapReadingCompany]

The leader had a sling psychrometer when I was a kid in the boy scouts.

[@tomtom4405]

@@TheMapReadingCompany had to Google that one ;) wow that's the grandfather of whirling hygrometers!

[@leegosling]

Back I. The 89s I bought a new fangled watch. Had a temperature sensor. Great thinks I. I can monitor temp to understand what’might be affecting the snowpack (obvs snowpack history the key, not the day fluctuations, but major warming if I’m all wrapped up, yes)… Bought it, used it. Realised it very accurately told me the temperature up my sleeve. Now use an external temp sensor on my rucsack strap just like the the ranger beads. Look like a climbing nurse but hey ho! Lol… Nice video one again.

[@stevemuggleton8936]

Another great video, timed perfectly to educate and inform, while I have my breakfast. A great way to start the weekend.

[@gordonjackson2655]

Wonderful, thank you. I watch all your videos. Have you considered a wind shied for your mic? Performing singers like myself use them all the time I know this isn't in your remit, but I love the times when you talk about local history. I live in the West Yorkshire Penning foot hills, we have a huge amount of geological and social history here. I don't think you would have the time, however, short videos (5 or 6 minutes?) on local lore would be lovely.

[@jeffreyalmond7376]

As ever very interesting video thank you.

[@tomconway8881]

Well done video. Thanks

[@vk3dgn]

Thanks, maybe you could have a crack at 'dew point' next and try to explain how things get colder than the surrounding air (black body radiation) 🙂

[@LoremIpsum1970]

Nice video. On the subject of weather and clothing, how about a review of your Velez Evolution? Wouldn't mind a full clothing, layer-by layer recommendation by weather, if that's something you haven't done before...

[@Inkling777]

I notice you're often standing next to stacks of stones such as cairns and walls. That seems to be very British. You might do a show on what they mean historically, particularly as indications of location. Do they have names? Are they used for navigation?

[@TheMapReadingCompany]

In this video the large piles of stones are called "Two Lads". I think I explain them at around 10:00 mark.

[@dougsundseth6904]

Water vapor is much less dense than air. (Water is 18 grams per mole, oxygen is 32 g/mol, and nitrogen is 28 g/mol). This is crucial for pilots; Humid air has a higher density altitude than dry air. The problem with cool air, is that if your clothing gets damp, it takes a great deal of energy to evaporate that water (540 calories per gram).

[@redf7209]

You can get little windchill thermometers keychain size that you can attach to your rucksack. Not sure how accurate they are.

[@manfredconnor3194]

Cluff from the German "Kluft" = "Gap". or from Swedish "Klüft" = "Divide"

[@philipoakley5498]

The comment about 'water being denser than air' isn't quite right/appropriate. The O2 and N2 molecules are atomically heavier than the H2O molecules as vapour. What is true is that it takes a lot of heat to vapourise the moisture that is on our skin, plus you have to heat the existing water molecules in the damp air (especially if it's saturated air). The fancy chart that covers the heat and moisture capacity of air is called a psychrometric chart - it's also very interesting for household moisture, condensation, mould and rot, but needs a few videos to explain ;-). The other misunderstanding is that the [repeatable] science equations are based on cooling a steel cylinder so don't quite reflect our real world experience. As you not a good jacket to keep the wind off makes a big difference.

[@simongee8928]

One point to be considered is people's 'vulnerability' to cold; some appear to be more perceptible than others. Although this may simply be psychological, it also may have a bearing on how fit someone is.

[@TheMapReadingCompany]

I did a “lot” more filming than was in the end edit 😊 - sometimes I have to remember it’s KZbin video and not a tv documentary, so a lot of what I do is eventually not in YT video. I’ve just watched the edited out sections and one of them was this. +++++++ Physiological differences mean that some people perceive cold faster than others; at the same wind speed and temperature. As an example larger and bulkier people lose body core heat slower than thin people due to the greater resistance / insulation provided by deeper skin, dermal and lipid layers. So they’re less susceptible to hypothermia. Of course this also means that, as less heat is transported to the skin, their skin cools faster and they are more prone to frostbite. Conversely thinner people are more at risk from hypothermia and less liable to get frostbite in the same conditions.

[@simongee8928]

One interesting thing is that I have Raynauds and despite having spent a lot of money on various types of gloves over the years, I still get cold hands when cycling or walking in cold conditions. 🤨

[@nikob5899]

So do I! I have Reynauds - I feel your pain. I'm an athlete and I suffer. Even when you finish and get home. The trick for me is to jump into the shower asap as otherwise my hands go white very quickly!😢 or soak them in hot water. P.s I use those heat packs now. Stick one in my gloves. They are amazing!😊

[@vicf5726]

Hi, love your videos, relate entirely to your waffle (don't stop) take a look at 'Essentials of Sea Survival' by Frank Golden and Michael J. Tipton. worth a look, when I was instructing sea survival courses (20 years ago) this book was the go too reference, I hill walk, and climb badly, but this book does have relevance. best regards.

[@hissingman]

Спасибо за отличное видео! Вопрос: как пользоваться функциональной квадратной шкалой Ромера (GPS romer scale) на компасе?

[@richardsherburn4816]

And when ambient temperatures is above 37C we have Wind Warm Factor? That would be a good one for the Met Office to really scare us with😉

[@markmiller8486]

Paul Siple died in 1968 at the age of 59. Charles Passel died in 2002 at the age of 87, but he felt like 68. 😀

[@j_omega_t]

Your tangents are as good as your main points!

[@mihailvormittag6211]

👍

[@nikob5899]

Do you ever comment?😅

[@mihailvormittag6211]

@@nikob5899 😀 I even asked you questions and you and you answered them. It was about setting up my Banana Pi M2 Zero:I had trouble booting into Armbian.

[@iterato1]

Your waffles are the best. Also no chance of any unhealthy calories.😂

[@dcfarouk]

Other than the knock off dirt cheap compasses in the market, which brands would you recommend and which you would advise to steer off ??? thank you.

[@inregionecaecorum]

The reason that British cold is worse than any other is the dampness, I think the Romans knew that.

[@philipoakley5498]

and the variability! 🌦

[@leegosling]

Aye, but they knew how to beat themselves with nettles until they felt warmer. 😂

[@philholman8520]

You had your gloves on but not your hat!?

[@simongee8928]

On that point, I've never seen Bear Ghrylls wear a hat on any if his adventures.

[@tomtom4405]

He's filming, probably puts his hat back on after that. BTW.. The ultimate hat for cold damp UK conditions is the Mountain Equipment Citadel Hat.

[@simongee8928]

My preference is an army beret. Being wool, it's warm, doesn't absorb rain easily, can't blow off in the wind and fits easily under the hood of a waterproof when it does get nasty. 😁

[@tomtom4405]

@@simongee8928 they can blow off, that's why you have to remove them if you go near a helicopter

[@simongee8928]

@@tomtom4405 Which is why I don't go near whirlybirds - ! 😆

[@jimjasper9851]

Another proper waffle, proper job.🦘🇦🇺👍🏼