WeatherWatch.co.nz is fielding questions from New Zealand and Australia with regards to the ash cloud over the two countries.  We’ve tried to address the main questions below…

Ash Cloud – FAQ

What volcano is erupting?  The Puyehue-Cordon Caulle volcano in Chile began erupting on June 4.

If Chile’s to our east, how come Australia is getting the ash before us? Away from the equator the wind travels from west to east (our prevailing wind is a westerly, it’s the same in Chile).  So even though Chile is much closer to our east, the ash is being blown eastwards, 9000kms around the globe and then coming in from our west or south west.  In fact, it’s now going around and around the globe.

Outside of Chile, how come Aussie and New Zealand seems to be the worst affected?  New Zealand is the only other land mass as far south as Chile.  Some maps, such as the satellite map to the right of this page, are stretched to fit into rectangle boxes, but in reality the South Island juts down further than Australia does.  (see map below).  Australia is also fairly far south, especially Tasmania and Victoria.

Why are some airlines flying while others are not?  You’d need to ask your airline.  Our belief is that conditions, for the most part, are completely safe to fly in and we are unsure why some airlines are placing blanket bans on travel during ash cloud events when the ash ceiling is 20,000 feet and above.  We have no further comment on this.

What happens if a plane flies into ash?  The ash may be very fine but it can choke engines causing them to shut down, while at the same time it literally sand blasts the cockpit windows making them almost impossible to see out of (and can remove the paint off the jet).  Planes can safely fly above it, or under it – but cannot fly through it.  To get above the ash they need to firstly fly around it, then climb up.

Will the ash affect our temperature?  It’s possible, when the ash is thick, that it could lower our temperature by a degree or two during the day, but our feeling is that mostly we won’t even notice it.

I collect rain water from my tank – should I disconnect this until the ash clouds clear?  No, the ash isn’t actually falling to the ground here, unlike when Ruapehu erupted.  In this case the ash is extremely fine and is being carried between 6 and 11kms above the earth and is travelling at well over 100km/h eastwards.

I have asthma, should I be concerned? The ash isn’t falling to the ground here so we don’t anticipate any serious complications.  Any ash that does find its way to the ground will be almost undetectable.  If you are concerned or having breathing difficulties please check with your doctor.

When will it stop?  That depends on when the volcano stops erupting.  The wind flow pretty much means New Zealand and Tasmania will remain at a high risk for ash during this volcanic event which could last weeks or even months.

Can we see the ash cloud?  During the day it is very hard to see, but it may make the sun pale and the sky less blue.  During sunrise and sunset it is most noticeable, creating fiery red skies.  On a clear night it may also limit the number of stars we can see.

Will it affect Auckland airport?  The ash itself won’t physically affect any airports, but the further north the ash cloud goes then the further planes have to fly to be able to safely climb to a higher altitude away from the ash.  At this stage we don’t anticipate any major problems flying from Auckland (with the exception of Qantas and JetStar) to most international locations, but this is an ever changing situation, so check with your airline if you’re concerned.

What do you think are the highest risk routes in NZ?  We can’t answer this as it changes daily.  Check with your airline.

What do you think are the highest risk routes in Australia?  We can’t answer this as it changes daily.  Check with your airline.

Can you advise us of which airlines are operating and which flights are affected?  No, we suggest you contact your airline for this information as there are too many for us to monitor effectively.

– This information was produced by WeatherWatch.co.nz and is intended to address the questions we are receiving.  Official information on the ash clouds can be found via MetService, CAA and BOM.