It's not the humidity, it's the heat
Jul. 13th, 2005 11:22 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
cincinnatus_c
Some years ago, I noticed that the weather forecasts in the Toronto Star--I'm pretty sure the forecasts came from Environment Canada at the time--would call it "very warm" when the forecast high temperature was 30 or 31C, and "hot" if it was 32C or higher.
I wish someone would come up with standards like that for humidity--because whenever it's hot, everyone says it's humid, because as we all know, it's not the heat, it's the humidity. You learn that esoteric bit of knowledge as a child, and then for the rest of your life you feel sophisticated when you say it's "humid" when it's hot. *Even the weather people on TV* do this, but of course most of them don't seem in any particular way qualified to talk about the weather. (It's amazing that Susan Hay on Global has been doing the weather for so many years and *still* *knows* *nothing*.)
The guy on the local news was driving me nuts the other day saying it was going up to 33C but would "feel much warmer than that with the humidex advisory". (Actually, the forecast high humidex that day was 39, which is fairly normal if not a little low for a temperature of 33C, so that day's 33C was, in fact, going to feel very much like your average 33C, not a lot warmer.) But I'd never seen this guy before, and later in the show he reappeared as the sports guy. Yeesh.
This, by the way, is another one for the category of everytime-the-newsmedia- reports-on-something-I-know-about-they-get-something-wrong. (And I know this, and yet I otherwise trust them more or less completely anyway. Which disturbs me, although it actually is a rational strategy ... *for Good Davidsonian Reasons*, as Prado might've said back at Queen's.)
Anyway, today (on this *very humid day*, what with the *humidex advisory* and all--though the humidity has, actually, been building for the last several days), roughly where I am, the highest temperature recorded on Environment Canada's hourly observations was 34C; it was 34C on four hours, with the highest dewpoint for any of those hours being 18C, for a relative humidity of 38%. The highest hourly dewpoint of the day was 19C. At Toronto Pearson, meanwhile, the high temp was 35C, with a dewpoint of 19C, for a relative humidity of 40%; the high dewpoint was 22C.
I'm thinking of keeping a running tab on these things here, to see, generally speaking, what *really is* humid. That'd be a lot of bother, and a lot of blather, though. But, dammit, somebody ought to do it!
My working view is that "humid" starts at a dewpoint of 20C, and "very humid" at a dewpoint of 23C. (The highest observed dewpoint I've noticed in Canada was 26C, earlier this year, at Toronto Island.)
Now, notice that what I'm primarily interested in is *dewpoint*, not *relative humidity*. Relative humidity is in fact important if you want to know how quickly your lawn or your skin is going to dry out, and how fast your skin dries out is in fact the important thing with regard to how much of a cooling effect the air is going to have on your body due to evaporation. However, when the overnight temperature falls from a daytime high of 30C to match the dewpoint of 15C, for a relative humidity of 100%, it doesn't make much sense to say that, while it was quite dry during the day, it is now extremely humid.
In other weather news (this is not Part W in an Occasional Series, but it might have been), the remains of Hurricane Dennis were supposed to affect our weather approximately now, but instead veered *west* toward Chicago. This is insane. I've never heard of any such thing. I've also never heard of a tropical storm affecting the southern Ontario weather before September, maybe late August, and this was the *second* one that was supposed to so far this month. *And*, Dennis was the third or fourth named storm (I don't know about the "A" one) that formed in the Caribbean or Gulf of Mexico--I'm pretty sure that usually doesn't happen much until late in the season; usually early-season tropical storms get a head of steam up coming across the open Atlantic (as another one is doing presently). Anyway, as far as I know, this is crazy (I mean, the weather *here* is crazy--it's been 35-36C in *Moosonee* all week, ferchrissakes!), but no one seems to have caught on.
Well, except the Cubans. Someone forwarded to a list I'm on a piece (probably from some group of socialist scientists) about a panel on Cuban TV, featuring Castro himself, noting that Castro et al. had mentioned how unusual it was to have such a strong Caribbean hurricane this early in the season.
I wish someone would come up with standards like that for humidity--because whenever it's hot, everyone says it's humid, because as we all know, it's not the heat, it's the humidity. You learn that esoteric bit of knowledge as a child, and then for the rest of your life you feel sophisticated when you say it's "humid" when it's hot. *Even the weather people on TV* do this, but of course most of them don't seem in any particular way qualified to talk about the weather. (It's amazing that Susan Hay on Global has been doing the weather for so many years and *still* *knows* *nothing*.)
The guy on the local news was driving me nuts the other day saying it was going up to 33C but would "feel much warmer than that with the humidex advisory". (Actually, the forecast high humidex that day was 39, which is fairly normal if not a little low for a temperature of 33C, so that day's 33C was, in fact, going to feel very much like your average 33C, not a lot warmer.) But I'd never seen this guy before, and later in the show he reappeared as the sports guy. Yeesh.
This, by the way, is another one for the category of everytime-the-newsmedia- reports-on-something-I-know-about-they-get-something-wrong. (And I know this, and yet I otherwise trust them more or less completely anyway. Which disturbs me, although it actually is a rational strategy ... *for Good Davidsonian Reasons*, as Prado might've said back at Queen's.)
Anyway, today (on this *very humid day*, what with the *humidex advisory* and all--though the humidity has, actually, been building for the last several days), roughly where I am, the highest temperature recorded on Environment Canada's hourly observations was 34C; it was 34C on four hours, with the highest dewpoint for any of those hours being 18C, for a relative humidity of 38%. The highest hourly dewpoint of the day was 19C. At Toronto Pearson, meanwhile, the high temp was 35C, with a dewpoint of 19C, for a relative humidity of 40%; the high dewpoint was 22C.
I'm thinking of keeping a running tab on these things here, to see, generally speaking, what *really is* humid. That'd be a lot of bother, and a lot of blather, though. But, dammit, somebody ought to do it!
My working view is that "humid" starts at a dewpoint of 20C, and "very humid" at a dewpoint of 23C. (The highest observed dewpoint I've noticed in Canada was 26C, earlier this year, at Toronto Island.)
Now, notice that what I'm primarily interested in is *dewpoint*, not *relative humidity*. Relative humidity is in fact important if you want to know how quickly your lawn or your skin is going to dry out, and how fast your skin dries out is in fact the important thing with regard to how much of a cooling effect the air is going to have on your body due to evaporation. However, when the overnight temperature falls from a daytime high of 30C to match the dewpoint of 15C, for a relative humidity of 100%, it doesn't make much sense to say that, while it was quite dry during the day, it is now extremely humid.
In other weather news (this is not Part W in an Occasional Series, but it might have been), the remains of Hurricane Dennis were supposed to affect our weather approximately now, but instead veered *west* toward Chicago. This is insane. I've never heard of any such thing. I've also never heard of a tropical storm affecting the southern Ontario weather before September, maybe late August, and this was the *second* one that was supposed to so far this month. *And*, Dennis was the third or fourth named storm (I don't know about the "A" one) that formed in the Caribbean or Gulf of Mexico--I'm pretty sure that usually doesn't happen much until late in the season; usually early-season tropical storms get a head of steam up coming across the open Atlantic (as another one is doing presently). Anyway, as far as I know, this is crazy (I mean, the weather *here* is crazy--it's been 35-36C in *Moosonee* all week, ferchrissakes!), but no one seems to have caught on.
Well, except the Cubans. Someone forwarded to a list I'm on a piece (probably from some group of socialist scientists) about a panel on Cuban TV, featuring Castro himself, noting that Castro et al. had mentioned how unusual it was to have such a strong Caribbean hurricane this early in the season.
