Go Back  PPRuNe Forums > Flight Deck Forums > Tech Log
Reload this Page >

Is UV exposure higher at southern latitudes as it is in northern?

Tech Log The very best in practical technical discussion on the web

Is UV exposure higher at southern latitudes as it is in northern?

Reply

Old 10th Oct 2018, 14:20
  #1 (permalink)  
Thread Starter
 
Join Date: Dec 2011
Location: Tropopause
Age: 34
Posts: 86
Is UV exposure higher at southern latitudes as it is in northern?

Hello,

Hope everyone is having a nice day/week.
I know that the airline I fly for tries to spread the Polar routes, or high latitude routes at (70N) etc equally among all pilots. They try to monitor the exposure, but surely enough not to the extent where their primary concern is us over operations.
I was simply wondering if flying at southern latitudes of S20, inbound to Australia for example, has the same effect in terms of radiation?

Thanks for your input!
WhySoTough is offline  
Reply With Quote
Old 10th Oct 2018, 14:53
  #2 (permalink)  
 
Join Date: Feb 2001
Location: The Winchester
Posts: 5,005
You’ve asked about UV in the title then asked about “radiation” in the text...which is a bit confusing...

1. You are more exposed to ionising “radiation”, as in the sort of stuff the sun chucks out in Solar Flares and The Cosmic rays from deep space at high latitudes (specifically high magnetic latitudes), I suspect that’s why your company is metering your flights at high latitude...but that’s a different “animal” to UV.

2. UV is the electromagnetic radiation (with a wavelength just below that which is visible to the naked eye) ..that produces sunburn and your exposure to that is more dependant on the elevation of the sun, any cloud cover, thickness of the ozone layer, windscreen thickness and materials..probably plus lots more

To answer your question about Oz and being 20 south... well at those latitudes you are well away from the thin bit of the earths’s magnetic field around the poles and so are well protected from ionising radiation, so I wouldn’t be unduly worried about ionising radiation in flight...OTOH you are near the equator and I would however be more tad a bit cautious about the UV at ground level, e.g walking around without sunblock or any other form of UV protection whilst on a slip in that part of the world.
wiggy is online now  
Reply With Quote
Old 10th Oct 2018, 17:30
  #3 (permalink)  
 
Join Date: Jan 2008
Location: Denver
Posts: 824
Incoming solar radiation (ionized particles) doesn't recognize the human conventions of "north" or "south" - thus will be the same at 70N as at 70S. Although it may depend a bit on the season (local "summer" or "winter" months).

The main issue with the polar regions is that the ionized particles tend to follow the lines of Earth's magnetic field. They are focused like a flock of ICBM's into trajectories aimed into the polar regions, thus producing the Auroras (Australis and Borealis) - which are ionizing particles hitting the atmosphere molecules and making them glow (oxygen, red or green; nitrogen, blue or crimson). Thus the amount (and any risk) will be higher at 70N/70S than at 20N/20S.

If you are flying in the polar regions, and see the Aurora right overhead - you are in the "line of fire."
pattern_is_full is offline  
Reply With Quote
Old 10th Oct 2018, 18:08
  #4 (permalink)  
 
Join Date: May 2005
Location: F370
Posts: 187
There was a “hole” in the ozone layer, which allowed more UV through, but it has closed up in the years since CFCs were banned. It was located over Antarctica, at latitudes of more than 60S. Not an issue, even if you are flying to Hobart!
AtoBsafely is offline  
Reply With Quote
Old 10th Oct 2018, 18:42
  #5 (permalink)  
 
Join Date: Apr 1999
Location: Manchester, UK
Posts: 1,855
Our company uses Globalog which give a statistically based dosage figure based on which routes you've flown and when. Sometimes, not so often, we have pilots taken off duties. This mostly arises after a rash of UK-West Coast USA flts.

As for UV, my one piece of advice is invest in a good quality pair of wrap-around sunglasses -and wear them!
ShotOne is offline  
Reply With Quote
Old 10th Oct 2018, 20:16
  #6 (permalink)  
 
Join Date: Mar 2006
Location: USA
Posts: 1,157
Originally Posted by ShotOne View Post
As for UV, my one piece of advice is invest in a good quality pair of wrap-around sunglasses -and wear them!
...or fly at night
Check Airman is offline  
Reply With Quote
Old 10th Oct 2018, 20:18
  #7 (permalink)  
 
Join Date: Feb 2008
Location: USA
Posts: 89
UV has already been well covered above. Exposure to ionizing radiation is a function of:
1) Altitude (because the atmosphere attenuates the secondary radiations which cause this exposure, the primary radiation having had nuclear interactions with the upper atmosphere well above aviation altitudes)
2) Magnetic Latitude (because as you near the magnetic poles the magnetic field lines are increasingly parallel to the trajectories of the energetic particles and impede their progress less)
3) Solar cycle (because, perhaps a little counter intuitively, the primary source of this harmful radiation is galactic cosmic rays, and magnetic fields created by increased solar plasma help deflect these from Earth)
3a) ...the caveat!.. however certain solar events that can send streams of energetic particles towards Earth can cause localized increases.

Now the interesting trivia part....there is a region in the Southern hemisphere that behaves differently *BUT* it only affects altitudes 200km+ (so satellites, not aircraft)
https://en.wikipedia.org/wiki/South_Atlantic_Anomaly
ion_berkley is offline  
Reply With Quote
Old 10th Oct 2018, 20:33
  #8 (permalink)  
 
Join Date: Feb 2012
Location: USA
Posts: 190
NASA has it right

Originally Posted by Check Airman View Post
...or fly at night
It is largely due to concerns about ionizing radiation, that NASA has announced that all contemplated future manned missions to the Sun will be flown entirely at night.
Gauges and Dials is offline  
Reply With Quote
Old 11th Oct 2018, 01:35
  #9 (permalink)  
 
Join Date: Jul 2013
Location: Everett, WA
Age: 63
Posts: 1,848
UV is of minimal concern inside an aircraft - the fuselage will completely block UV (either aluminum or composite), and the aircraft windows filter out well over 90% of UV.
tdracer is offline  
Reply With Quote
Old 11th Oct 2018, 13:38
  #10 (permalink)  
 
Join Date: Dec 2003
Location: Tring, UK
Posts: 1,297
UV is of minimal concern inside an aircraft - the fuselage will completely block UV (either aluminum or composite), and the aircraft windows filter out well over 90% of UV.
10% of the incident UVA/B when you’re at 40,000'+ plus is very significant. Even 1% would be a worry in direct sunlight...
FullWings is online now  
Reply With Quote

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service