0-1% Humidity documented by the Bureau of Meteorology

[pgc hunter]

Extreme low humidity in Mildura today, punching the values into a calculator resulted in a reading of 0.4% humidity at 4:04pm. Air temp 30.4C, dewpoint -41.1C

A lot of people believe that extreme low humidity readings of under 1%, 2% etc and whatnot is the stuff of fiction, well, no it is not.

[johnno07]

That's quite incredible! I would be interested to know how that is actually physically possible.

[pgc hunter]

I got no idea, but evidently it is possible!

You can see that the wet bulb thermometer has failed a couple of times in those observations, which leads me to believe that the humidity got so low that it can't actually be registered. I am a weather enthusiast, and never seen a -41C dewpoint at 30C before in this country.

[gary]

Hi Sab,

As you alluded too, maybe it is due to an instrumentation error or some limitation of the
instrumentation?

It would be worth dropping a line to the Bureau and asking them.

If you pass on their response, I am sure many of us would be interested to
hear the outcome.

[johnno07]

+1 to this. I'd love to know.

[brian nordstrom]

:) Here is a photo of my clock on the side of my ute under cover , camping at 2.20 this afternoon , Kunanarra WA .
Brian.

[mental4astro]

During Thursday's horror fire run here in Sydney, WeatherZone had the temp at one point at 29, and dew point at -19.7. Had me do a double take.

forgot to mention, 4% humidity, njust about unheard of in Sydney.

[Blue Skies]

I think you'll find it is real. Kalgoorlie and the surrounding goldfields had something similar happen last week, too. I'm pretty sure I recall it happening a few times in the last 5 years or so here in WA, but not every summer, though.

Aha - here is the tweet, from the 15th Oct:
________________________
Michael Schultz ✔ @M_Schultz_10 (https://twitter.com/M_Schultz_10) My Oh My it's Dry! Mid afternoon in the #Goldfields (https://twitter.com/search?q=%23Goldfields&src=hash). #Meekatharra (https://twitter.com/search?q=%23Meekatharra&src=hash) 1% RH. Dew point -30. Temp 32. #Kalgoorlie (https://twitter.com/search?q=%23Kalgoorlie&src=hash) 2% RH. Dew point -25. Temp 32.
Retweeted by The WA Weather Group (https://twitter.com/TheWAWG)
______________________________

Ok, so it's not -41, but it is 1% RH! hmm, and the next tweet says the dew point got as low as -35. So there you go.

The only time I've really seen the wet bulb go kooky is during cyclonic events when the constantly strong wind dries the wet bulb out and then it does give false readings.

[pgc hunter]

It's real indeed. All surrounding stations have been recording humidities of 2-3% at the same time. The Mildura weather station is a reliable, active station, There is no reason to doubt the readings. Most people elsewhere in the world would find these extreme low humidities to be the stuff of fiction, but no way, it is very real. The instrument is reliable and functioning correctly, after cutting out a few times, the humidity readings do show a valid observation compared to other stations in the area.


That -41.1C dewpoint is legit. The dewpoint / RH readings cut out because the air became so dry in those instances that the wet bulb thermometer failed. And going by the latest obs it keeps functioning after dropping out multiple times, that tells me that the instrument is working properly.

I am going to contact the BOM tomorrow, this could well be world record....

[johnno07]

"Yeah man, but it's a dry heat!"

[kinetic]

Sab's thread made me pay more attention to the data recently.

Yesterday Adelaide recorded some pretty interesting dew point levels.
Around noon it was 36.7C , Dew Point -4.7 , RH 7%

http://www.bom.gov.au/products/IDS60901/IDS60901.94675.shtml

Steve

[tlgerdes]

:lol: You beat me too it!

[OICURMT]

I bet your thinking... "why did I buy a dew heater?"

[pgc hunter]

Speaking of heat, check this out.

Would be a sweaty observing session for sure!

[Shano592]

I recall that Ian Healy was remarking - during the Perth Test - that the RH dropped from 22% to 10%, between 8:30am and 10:30am. That seems like a sharp fall in just two hours. To me, anyway.

It might have been the second day's play, for those playing at home.

[mithrandir]

That's not unreasonable. Here at 06:00 this morning it was ~18C and 90% RH. At 15:00 it was ~42C and 10% RH. And that was with the garden sprinklers running all morning. Observe how the graphs are almost mirror images.

[gary]

Hi Steve,

Happy New Year.

Watching these numbers update every 30 minutes reminds me of the old saying that
a watched kettle never boils.

Mind you I'd hate to be inside that kettle right now.

[Terry B]

At least the evaporative aircon will be effective.:P