logoalt Hacker News

shitloadofbookstoday at 12:16 AM9 repliesview on HN

"Extreme Heat" seems to be 37-40 degrees Celsius which is bafflingly mundane to me as an Australian who grew up in rural New South Wales. We'd pack 30 kids and a teacher into an un-airconditioned classroom with just a ceiling fan and the windows open in that temperature.

I imagine the buildings there just aren't built to support that heat plus the body height of hundreds or thousands of attendees?


Replies

jcranmertoday at 1:55 AM

People tend to rely on air temperatures when in reality the lethality of heat is probably more linked to the wet-bulb temperature.

The human body has a natural resting temperature of about 37°C, and metabolism of course generates more heat constantly, so we constantly have to shed that heat. When the temperature is low, we can rely purely on conducting the heat into the atmosphere to shed the heat (which is probably why internal body temperature is higher than the atmosphere!). At higher temperatures, conduction is less efficient, or sometimes even adds heat load into the system (at above 37°C, obviously), so we start relying on evaporative cooling (i.e., sweat) to cool us down.

The wet-bulb temperature is the minimum temperature that can be reached by evaporative cooling. So when the wet-bulb temperature is in the mid-30s °C… people start to become literally unable to regulate their core body temperature, and the heat is lethal. Wet-bulb is largely a combination of the temperature and humidity, but unfortunately, it's not typically reported in most weather reports, so people go off of the air temperature (and the humidity) that is reported.

Which is a long-winded way of saying "the humidity matters a lot for how much a given temperature is bearable." I don't know what environment you come from purely by rural New South Wales, but my first guess is the semi-arid and thus low-humidity bush regions of the state, which means the apparent wet-bulb temperature of 37-40°C would be a lot lower than the equivalent 37-40°C for most of the humid continental climates of Europe.

maxericksontoday at 12:56 AM

Humidity makes a big difference in how stressful the temperature is (wet bulb temperature accounts for this somewhat). The age of the attendees and the tendency of the building to heat would also be factors.

human305893today at 12:30 AM

Euro buildings are built to keep heat in. Aus buildings are leaky tents.

show 1 reply
germandiagotoday at 1:33 AM

Spanish here. Same here.

I think they have been spreading the paranoia for years as if something abnormal was happening... I am not sure, that first thing. Second: even if the weather keeps shifting (I would say more slightly than what they tell us or continuously "suggest" with headlines in the media), these temperatures are bearable by humans with a few cautions depending on the age group.

I used to go jogging midday in summer in Spain, near Valencia, in the seaside. Almost 40 degrees (sometimes I guess 40 or more).

It is hot, true, but if you can resist this kind of impact and you do not expose yourself to the sun in stupid ways (like many hours in a row) nothing bad is going to happen to you.

The headlines are all the time alarming people and sensationalist, even if the cancellation is there.

show 2 replies
nomilktoday at 1:26 AM

And that was after running around a semi-arid playground playing 'tips' or touch footy during recess and lunch!

show 1 reply
weightedreplytoday at 12:54 AM

We need a humidity comparison to go with temperature.

I grew up in a humid city and summers were unbearable. Now I live in a dry climate and 30°C is pretty comfortable.

show 1 reply
tzstoday at 1:02 AM

How does the humidity in rural New South Wales compare to London?

show 1 reply
anthktoday at 12:57 AM

40C in the Atlantic Spain with the Foehn effect (weather for today and tomorrow) would make 30C in Australia a joke.

The humidity here it's hell. You feel 35C like ~42C in dry climates.

show 1 reply
winstonptoday at 12:17 AM

the British are notoriously sensitive to heat. They'll call 30 Celsius weather a heat wave.

show 5 replies