371–380 of 414 posts
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For people reading "web bulb" here and not having the least idea of what it is, first of all it's "wet bulb", and this article explained it very clearly to me: https://www.iflscience.com/environment/why-is-everybody-talk...
Seems like Wet Bulb is a more precise version of what some weather reporters call "Heat Index". Meant to measure how hot it actually feels on the skin. Is there any sort of formula mapping heat + humidity to wet bulb?
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95 Fahrenheit is actually quite survivable. It is dangerous for old people, young people, and the very sick when combined with sun exposure and other factors. I spent much of my life living in that temperature range without A/C, working outside during the day in the sun. It's hot but not going to kill you. In fact, there are massive homeless encampments outside my window right now in extremely humid, hot, Texas weath…
N.B. the 35c/95f temperature they're talking about is _not_ air temperature. It's 'wet bulb' temperature, or what the air temperature would be at 100% humidity. Only when the actual humidity is 100% are the two equivalent. Otherwise, the wet-bulb temperature measures the lowest temperature achievable by evaporative cooling. The survivability concerns of sweat being unable to cool humans below hyperthermic levels shou…
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https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6... "It is unequivocal that human influence has warmed the global climate system since pre-industrial times." "The likely range of human-induced warming in global-mean surface air temperature (GSAT) in 2010–2019 relative to 1850–1900 is 0.8°C–1.3°C, encompassing the observed warming of 0.9°C–1.2°C, while the change attributable to natural forcings is only −0…
I have seen that IPCC statement you quoted before and don't regard it as credible. Again, once again, over again, yet again, one more time, just from what I wrote, from either data or models, there is no credible evidence that CO2 from human activities has had, is having, or will have a significant effect on temperature. When there is credible evidence, I will pay close attention. The IPCC can say "unequivocal" all t…
But, as they say, you can't reason someone out of a position that didn't reason into in the first place.
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I'm in Denmark, when it gets 26 degrees here I drench my shirts in ice water and put in the freezer for a bit and then put on to cool down. I'm guessing, given what a wimp I am about the temperature, a few more degrees and I'm one of the first to die.
Always look on the bright side of death.
Unfortunately it looks like someone who didn't get it downvoted you. Welcome to HN!
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I did... and?
You come off as browbeating him, accusing him of not knowing things, when he said a small thing that was fully accurate if not precise. That's why you're being downvoted.
How is that fully accurate? It seems to me that "not very survivable" is not accurate and is an over exaggeration. I don't expect a 50% death rate, even 10% would be extremely generous. It would be like me saying linux desktops are very common.
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Swamp coolers cool based on evaporative cooling: water evaporating into dry air reduces the (dry bulb) temperature of the air. So with high wet bulb temperatures indicating air is already saturated with moisture, the swamp cooler won't work.
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.
Anyway, the best way to learn more about this is to search for resources describing the "psychrometrics of evaporative cooling". Psychrometrics is the study of the thermodynamics of air and water vapor mixtures. Learning about the psychrometric chart, in particular, is helpful since it is a very clear, expressive tool that will illustrates how adiabitic (no change in thermal energy transfer) cooling can occur by adding humidity to dry air.
I think this entry from engineering toolbox provides a good start: https://www.engineeringtoolbox.com/evaporative-cooling-d_698...
Kim Stanley Robinson's recent book The Ministry For the Future starts with a very disturbing scenario: A heatwave with a "web bulb" temperature of 35 Celsius. It turns out, in those temperatures, even young and healthy people can't survive. Combined with power outages, as happens in the book, everyone living under such a heat wave will likely die. It's looking increasingly likely that such heatwaves are possible in t…
It’s called wet bulb, not “web bulb”.
I too didn’t understand what Wet Bulb temperatures meant until I used this calculator: https://www.omnicalculator.com/physics/wet-bulb
95F TB (Temperature Wet Bulb) is when the humidity is 100% and it is 95F out. The lower the humidity, the lower the TB value. At 40% humidity and 120F temperature, you get 96F TB. Imagine 120F at 40% humidity. Insane, right?
That’s what kind of temperatures this paper is talking about: dangerously hot and humid.
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> going into cellar. The air will get cooler but the humidity will rise. If we are already counting on a wet bulb temperature of 35C, the humidity is likely already very close to 100%. Reducing the temperature is likely to be a net good.
That's false. TLDR: The air gets cooler but still can't cool you. Your body produces heat that has nowhere to go and you still die. Then the walls of the cellar heat up immediately, because cooling 100% humid air requires sinking a lot of energy. If you found yourself in conditions of an actual heat wave as described, you would despair at the fact the air can get cooler in your cellar but it doesn't cool you at all.…
While true about the conservation of energy, the drastic differences in both mass and heat capacity of air/earth mean the cellar walls will probably have no perceptible change in temperature.