Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

The emergence of heat and humidity too severe for human tolerance (2020)

advances.sciencemag.org

Post reply on HN
Print view View original

391–400 of 414 posts

Re: The emergence of heat and humidity too severe for human tolerance (2020)

#391

Post by bumby »

lmilcin wrote: post #383
Aeolun wrote: post #382

Earlier quoted context omitted.

> TLDR: The air gets cooler but still can't cool you. Evaporative cooling is not the only kind of cooling that exists. If this were the case you’d die of heat death standing in the middle of 100% humidity antarctica. If your cellar is cold enough you’ll be in a much better situation than before. You seem to assume that the moment you open your cellar door, all humidity and temperature will immediately equalize with t…

Again, completely wrong. 100% humid 0C air is still 0C wet bulb temperature -- perfectly good for cooling you down.

>Again, completely wrong.

You are saying the same thing as the OP.

There are generally two type of heat in this scenario sensible and latent.

Think about when you heat up water on the stove. If you were to graph the temperature T against the heat energy added Q, you would see the temperature gradually rise as the amount of heat was added. This is the 'sensible' heat. But at a certain point the water would hit boiling temperature. You're still adding heat but the temperature is no longer increasing so what gives? The energy is now going towards phase changing the water from a liquid to a gas. This is the 'latent' heat.

The OP is just saying there are more paths than just latent heat transfer, which is why they said you won't overheat in Antarctica if it's 100% RH. Your statement here is that evaporative (latent) cooling won't happen at 100% humidity but sensible cooling can still occur. You're both on the same page.

Re: The emergence of heat and humidity too severe for human tolerance (2020)

#392

Post by dotcommand »

Zenbit_UX wrote: post #326
djrogers wrote: post #285

Earlier quoted context omitted.

> en masse I'm not sure that phrase means what you think it means... Yes, there were ~600 tragic deaths in BC from the heat dome, but en masse means 'as a whole' or 'as a group', and a .012% death rate does not really qualify there.

If you understand French you'd know it just means in large quantities.

But we aren't speaking french. We are speaking english and in english en masse doesn't mean a tiny fraction of people/group.

Re: The emergence of heat and humidity too severe for human tolerance (2020)

#393

Post by exo-pla-net »

giantg2 wrote: post #384
exo-pla-net wrote: post #381

Earlier quoted context omitted.

This is silly/pedantic. He's talking about being in a typical house with a dead A/C, experiencing the equivalent of 70C. Please tell us how you're going to survive that circumstance. Answer: you're not. You're going to change your circumstance, since it's not very survivable . You're going to leave your house and try to find somewhere cooler. His statement is accurate if not precise.

Lol it is not the equivalent of 70C. Please see the other resources people have posted here about understanding wet bulb temperatures. Even a wet bulb of 35C can be tolerated by most for hours - 70C could not. I would not leave my house. My house has insulation and thermal mass, which would delay the tempature from reaching that level until later. I could use water to cool myself, whether in the bath tub or a trashca…

You're describing tactics that will lead to your tenuous survival. If the heat doesn't last too long. And if you don't have anyone else is your house, not a likely circumstance globally considered. Almost like 35C wet is not very survivable. Your claim that 35C wet can be tolerated by most for hours contradicts the article, and your claim that it's more tolerable than 70C dry contradicts the concept of heat index. Anyhow, you're welcome for my charitably stepping in to let you know why you're being downvoted. You're stuck on pedantry and straw manning and pointless unproductive argument. The Hacker News collective had you pegged, and I'll just join the downvote parade and ignore your type in the future. I'm out.

Re: The emergence of heat and humidity too severe for human tolerance (2020)

#394

Post by Nialna »

Johnny555 wrote: post #37

Similar question to this that I've been wondering this wildfire season -- at what point is AQI (Air Quality Index) too severe for human tolerance? The scale tops out at 500, what happens to a person if the air is even worse than that? Some sensors near Medford, OR are reading in the upper 400's and even low 500's -- what happens if it hits what would be the 1000's if the scale went that high? I'm mostly thinking of p…

Well it already happens when big wildfires happen and people have dangerous air around for days. In the short term, keeping everything closed and using masks is probably enough.

If you mean as a permanent thing, you'd need houses to start having filters on air intake and no openable windows, with instead all air being circulated by the place that has a filter

Re: The emergence of heat and humidity too severe for human tolerance (2020)

#395

Post by markenqualitaet »

marcyb5st wrote: post #258
Sharlin wrote: post #225

Earlier quoted context omitted.

I'd expect the land to become unproductive first . A huge amount of agricultural land is threatened by the climate change, accelerated by other anthoropogenic effects such as soil erosion due to deforestation. Besides drought, heat, wind, and excess rainfall, there's flash floods caused by melting glaciers in the Alps, Himalayas, …

True. And at that point I really believe unrest will be widespread. The saying "We are 3 meals away from anarchy" will prove its veracity.

I think Bangladesh is also scheduled for certain crisis.

And let's be real, no wall (or frontex and the like) will ever keep out billions of people. If the world doesn't get its shit together and respond globally and collaboratively now, this will get ugly beyond imagination and no one, no matter the edgy coldness of their x-first attitude, will come out of this recognizable. People won't just die politely, much less when informed about who's to blame for all this hell.

I think there may be even possible consequences beyond everyone's worst nightmares when we see massive ecosystem collapses. What is it gonna be like, if you have unimaginable fields of mold and bacterial overgrowth? The winds bring Sahara's heavy mineral dust to Europe now, I am sure spores and toxic particles fly much better tomorrow...

Re: The emergence of heat and humidity too severe for human tolerance (2020)

#396

Post by hasmanean »

ericmay wrote: post #303
rstuart4133 wrote: post #200

Earlier quoted context omitted.

> Extreme heat (including heat waves that exceed this threshold) happen semi-regularly The threshold is wet bulb 35 for 7 hours. That is when fit young humans can't survive. Older people die well before that of course. And no, it doesn't happen regularly. I wasn't aware it had happened at all, although others here say it has. But it has come close. From https://www.telegraph.co.uk/global-health/climate-and-people...…

> Jacobabad crossed the 35C wet bulb threshold in July 1987, then again in June 2005, June 2010 and July 2012. Each time the boundary may have been breached for only a few hours, but a three-day average maximum temperature has been recorded hovering around 34C in June 2010, June 2001 and July 2012. Jeez what a hot place... Any idea what geographic features make it so dang hot? It's not too far from water (just lookin…

I lived about a hundred miles from Jacobabad in 1987. It was known as the hottest place in the world then along with Sibi to the north. I remember 50C temperatures but it was dry and I used to walk outside to the market around noon. Once my school principal saw me walking without a hat that summer and lectured me about safety but I didn’t feel anything bad. It helped that I was thin and had a high surface are to volume ratio so heat never bothered me. My father worked for Exxon and we had free electricity and every house had massive 8-ton air conditioners, so the heat was never a problem for us.

Sibi is in a hollow formed by some mountain ranges to the north. Perhaps hot winds from the south get trapped there. Not sure about Jacobabad though…could never find any reason why it was so hot.

Another time I was in a car with no AC right after a rainstorm, and it was so hot in the backseat that every time the car stopped the heat became unbearable. When the car was moving we had some wind and it helped.

In Canada I’ve always noticed the temperature can be 5-10 degrees cooler under trees in a forest. Not sure if it’ll be so cool with high humidity but certainly trees will block the sun and trap air cooled by the ground, so they are the best defence against global warming.

Re: The emergence of heat and humidity too severe for human tolerance (2020)

#397

Post by hasmanean »

giantg2 wrote: post #362
Izkata wrote: post #330

Earlier quoted context omitted.

It's not about saving water, it's about immersing yourself in water. You seem to have a different natural disaster in mind.

It is about conservation of water because as the person pointed out, you can't have a bunch of people running water continuously. You can store the water in a trash can or other large container. You can immerse yourself, or parts of yourself, in this water. You can even make a gravity shower to reuse the water since it's used for cooling and not cleaning. Replace the water when it gets too warm. This would greatly re…

In some places people used to pump groundwater out of the ground to use. That water should be at a temperature of around 10-20C. So you could soak your feet in that to cool off.

Re: The emergence of heat and humidity too severe for human tolerance (2020)

#398

Post by hasmanean »

wtallis wrote: post #107
newbamboo wrote: post #80

Earlier quoted context omitted.

Dehumidifiers are a thing. I presume that having water and electricity is a bigger problem for most people, but I’d love to be educated more on the problem, if you have links or literature.

Dehumidifiers are air conditioners that put the heat back in the air they treat instead of dumping it outside. Your electricity would be better spent operating a real air conditioner.

Or you could use an Einstein-Szilard (aka absorption) refrigerator that works without electricity. It’s driven by heat. It uses 3 gases (butane, ammonia and water.) It has no moving parts so it’s safe.

Someone could make a “Einstein dehumidifier” using 19th century technology and roll it out across the world. If embedded in buildings it could cool them constantly with no electricity required.

Re: The emergence of heat and humidity too severe for human tolerance (2020)

#400

Post by Qem »

beamatronic wrote: post #301
jiggawatts wrote: post #143

Earlier quoted context omitted.

> Combined with power outages, as happens in the book, everyone living under such a heat wave will likely die. That's an exaggeration. Extreme heat (including heat waves that exceed this threshold) happen semi-regularly, and the death rate when they occur is nowhere near 100%. More like 0.1% or less. Electrically-powered air conditioning is not the only way to cool a human body. Simply escaping to an underground or s…

The smart thing to do now would be for everyone around to world to start digging underground relief shelters.

Probably everyone painting their roofs white would help too.
Post reply on HN