Volcanic Ash - Cordon Caulle

[Phantom]

Here is a sat pic taken on June 13 2011

[rochedalescan]

Wow now I understand why they were delaying flights ..

[Stretch]

Very nice how it left Tassie alone - pity no one could fly in our out haha

[Phantom]

Well, if u look at the picture, you may note they have identified Tasmania as not apart of Australia!

The next plume is far worse....

Here is the link to the BOM providing all the latest info on the VA

http://www.bom.gov.au/products/IDD65290.shtml

[AIRMAN]

Here is a sat pic taken on June 13 2011

In this photo, I would have confused that with a very cold air mass coming from Antarctica. So its confirmed as VA?

I have heard Commercial Aircraft reporting very cold air above FL350, sometimes minus 70C. Normally at FL350 the outside air is minus 30C. So when you are a passenger sitting in the relative warmth and comfort of your airplane, spare a though for the hostile air which is passing outside your window at 800kph

[TahiiNZ]

Interesting about the very cold air. I was last working on Thursday, and the air up at FL350 was looking normal on the graphs. For it, that low, to be -70°C, is extraordinary. Id' almost go as far as saying faulty sensor. Coldest we've ever seen it at work is -85°, but thats more like 70-80kFt (i.e. FL700-800)

[Phantom]

You in the tropopause or troposphere?

Near the equator?

What was the ISA deviation?

Sound like a dud SAT probe....

[Phantom]

Looks like the cloud may knock out adelaide, Melbourne, Canberra Sydney and stretch into the Tasman again (from the latest predictions)

Terrible news for the travelers and airlines again,

[TahiiNZ]

You in the tropopause or troposphere?

FL300, aka 30,000ft aka 10km high is around about the troposphere/tropopause boundary for here in Invercargill NZ.

I have a balloon up at the moment, 10km high (give or take 20m) is -58.9°C at the moment, gets about 5°C cooler before levelling out into the tropopause.

Also, radio tells me Sydney and Melbourne Airports closed from afternoon our time, and NZ airports affected as of tomorrow (no planes to stuff with my balloon launch times!).

[Phantom]

The temperature given by the aircraft (or probe) is dependent on many factors.

ISA Deviation, Location (relative to Tropopause/sphere) and how accurate the sensor is.

In the cockpit, the information is given as either a SAT (saturated air temp), TAT (total air temp) and ISA deviation (cant be worked out from many different sources)

The information given in an AIREP is the SAT which makes allowances for the friction and heat buildup on the temperature probe. Effectively the should be fairly close to the of the WX ballon temp (but since they cant launch balloons everywhere and their location cannot be controlled - they use the AIREP to help model the charts)