351–360 of 414 posts
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…
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Wet bulb requires it to be... you know... wet. Not very practical to include in your electronics. I don't know exact method used but I can assure you, there is no water reservoir in any of my gadgets:)
It looks like I’m confusing a classic psychrometer with more modern ones. The modern ones still use absorption of water to change some physical property like capacitance or resistance but this is also why they need to be continually calibrated against a true dry/wet bulb hygrometer. My experience is that they tend to get out of cal quite often which can lead to bad scenarios, like if using enthalpy setback for air-ha…
Psychometer is completely different idea.
Yes, measuring humidity reliably is a difficult problem as basically any other measurement that requires direct exposure of eroding/corroding components and fragile electronics to elements.
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> going into cellar. The air will get cooler but the humidity will rise. You are going to die, unless you can cool the air DRY BULB temperature below 35C. Don't you mean wet bulb temperature? Why would you need a dry bulb temperature below 35C? > It will be shitty, wet, 100% humid, hot place, to sit half a day in with your family, kids and neighbors that don't have an expansive cellar like you, but at least you will…
I mean DRY BULB temperature. Reducing dry bulb temperature == removing heat. Reducing wet bulb temperature == removing humidity. But it doesn't matter a lot, because at 100% humidity (required to spontaneously dew humidity out of air) dry bulb temperature equals wet bulb temperature. Dry bulb changes indpendently of wet bulb temperature but cannot be lower than wet bulb temperature. Because when air temperature (dry…
This isn't the best interpretation. Both reducing humidity and reducing dry-bulb temperature can reduce the amount of energy in the air.
Take a look at a psychrometric chart [1]. If you hold the humidity constant and reduce dry bulb temperature, you indeed reduce the enthalpy (what I interpret you mean by 'heat'). Likewise, if you keep the dry-bulb temperature constant and reduce the humidity you also reduce the enthalpy
To your point, this is why fixed dry-bulb economizers aren't recommended in humid climates as a means of conserving air-conditioning energy by bringing in outside air but enthalpy controllers are allowed across all zones.
[1] https://www.engineeringtoolbox.com/docs/documents/816/psychr...
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It looks like I’m confusing a classic psychrometer with more modern ones. The modern ones still use absorption of water to change some physical property like capacitance or resistance but this is also why they need to be continually calibrated against a true dry/wet bulb hygrometer. My experience is that they tend to get out of cal quite often which can lead to bad scenarios, like if using enthalpy setback for air-ha…
Well, wet bulb thermometer works specifically by evaporating water and measuring temperature. Psychometer is completely different idea. Yes, measuring humidity reliably is a difficult problem as basically any other measurement that requires direct exposure of eroding/corroding components and fragile electronics to elements.
"A psychrometer, or a wet and dry-bulb thermometer, consists of two calibrated thermometers, one that is dry and one that is kept moist with distilled water on a sock or wick. At temperatures above the freezing point of water, evaporation of water from the wick lowers the temperature, such that the wet-bulb thermometer will be at a lower temperature than that of the dry-bulb thermometer. "
https://en.wikipedia.org/wiki/Hygrometer
The psychrometer just compares the wet and dry bulb temperatures to arrive at a relative-humidity value. I.e., it still operates on the principle of a wet-bulb thermometer.
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There's historical evidence of global fires & mass extinctions due to Geomagnetic excursions, which we are currently going through right now, leaving Earth vulnerable to space weather. https://www.researchgate.net/publication/305971138_Evidence_... https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018RG00... We are in for a bumpy ride of wild temperature swings & extreme terrestrial weather driven by space weather…
No. IPCC 6th assessment report, summary for policymakers, page 8/42. Read it. IPCC is the most conservative science body ever created. It comprises hundreds of scientists from all over the world, including Saudi Arabia and others, who need to unanimously approve each sentence. The role of human emissions in the current warming has been assessed without any possible doubt.
The role of human emissions as the key driver of climate change has plenty of doubt & plenty of money involved pushing a pre-determined outcome with the purpose of imposing taxes & centralizing power.
In the meantime, humanity is left unprepared for cosmic & geologic events (volcanic activity is driven by ionic activity from space) that are going to occur within 1-2 decades which will have drastic impacts. Since other planets in our solar system are seeing major perturbations in their climates, we should take nature more seriously.
There are other models that more heavily use solar forcing, which are gaining in number. It seems like there is increasing momentum in models which feature Solar forcing & recognizing the Geomagnetic field strength as a major factor in climate. These are all just models, but there are a growing number of scientists who are taking natural cycles more seriously than the APGW crowd.
http://www.raa-journal.org/docs/papers_accepted/2020-0449.pd...
The big global institutions are behind APGW with $Trillions invested in that industrial complex, but there are many independent scientists who are finding that natural phenomena have always been and are still the key drivers of climate change. My bet is on nature, not the wealthy 1% owned institutions with PR departments & editorial spin.
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Yes, this is completely correct. I would add the wet bulb thermometer needs large evaporation area (so the sock cannot be too wet and definitely you can't put it in the bucket) and/or some airflow around it. Otherwise it will show some temperature between actual dry bulb and wet bulb temperatures. In practice, nobody seriously uses wet bulb thermometers outside of school experiments because they are such a PITA. It i…
> nobody seriously uses wet bulb thermometers outside of school experiments because they are such a PITA. It is easier to just measure dry bulb temperature and humidity How is humidity typically measured? I was under the assumption a hygrometer uses both dry and wet bulb measurements.
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I wonder how practical it would be to sink 30 foot deep concrete tube shelters with a ladder and a lid. They could serve as emergency daytime shelters and someone could climb out at night to search for a location with working power or cooler weather.
I do wonder, if wet bulb temperature is a function of temperature and humidity (assuming reducing temperature requires electricity usually) will the real trick to reduce mortality will be to reduce relative humidity in a confined space. A supply of emergency desiccants somewhere at home may be an avenue worth exploring.
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This is all fascinating stuff to me, I'd never really heard of wet bulb before. Quick question though: how does the pressure difference play into this in a basement? As far as I'm aware below ground pressure and voids under basements tend to cause pressure differentials in even non-AC basements (causing radon issues where I'm from)? I assume this would help a cellar situation in the event of power outage as air even…
The pressure difference between your backyard and your basement is for all practical purposes null. It is also orders of magnitude smaller than those caused by gusts of wind and changing weather.
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> nobody seriously uses wet bulb thermometers outside of school experiments because they are such a PITA. It is easier to just measure dry bulb temperature and humidity How is humidity typically measured? I was under the assumption a hygrometer uses both dry and wet bulb measurements.
The traditional 5 dollar analog hygrometer uses a paper/metallic strip coil: https://www.youtube.com/watch?v=jCUHDFYdG44
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Having lived in Singapore for five years (2012-2017) (and worked out in the field for about 50% of that time) I can say that Singapore is one of the milder places to live. It never ever gets particularly hot (I genuinely can't recall a 100+ degree day in the entire time I was there), and the humidity, while, "sticky" is never really extreme. The thing that gets to you is that the climate never seems to change (with t…
> I can say that Singapore is one of the milder places to live. It never ever gets particularly hot Singapore is almost exactly on the equator. UV readings get up to 11 each day (extreme), whereas the most I ever saw in say SF was 5. Your experience is one experience, mine is that it's a sauna every day of the year. I've experienced extremely hot days in terms of subjective experience of WBT as explained in article.…
In the time I spent in Dubai (about six months) in comparison, I had to seek shelter from the heat/sun a half-dozen times, and came close to heat-stroking a bunch of times. That was after 4+ years in Singapore.
I drank a lot of water in Singapore - but never, in a million years would I have gone on a trek like MacRitchie reservoir in Dubai - and in Singapore I took my 65 year old mother through the entire loop.
Just completely different environments - Singapore is not the type of environment being discussed in the original article.