MESOSPHERIC GRAVITY WAVES:

[johnm]

There is an interesting section on MESOSPHERIC GRAVITY WAVES on spaceweather.com today link here.

The report states that the Mesospheric Gravity Waves have been observed which the report states are related to Sprites above large thunderstorms. There is a movie on the link from the page. The waves imaged seem to have some similarity to NLC but it is difficult to make any direct comparison as the images are in infra-red. As they are in the mesosphere they are in the same part of the atmosphere as NLC

Does anyone have any idea if NLC are visible in the infra-red and if so what they look like ?

They were over New Mexico so are a long way South for NLC but could there be a connection ?

Regards

John

[Bill W]

Hi,
Have a look at my video from last night. It shows the classic standing wave pattern of a gravity wave to the right and centre.
NLC aren't very visible in the near IR due to the particle size. I've tried to record them at 850nm and 1000nm. They look like a faint hazy veil only.
On the other hand at short wavlengths they are very efficient scatterers. I don't know if you've seen this video

www.youtube.com/watch?v=I26xnuxUtVE

but it shows the NLC ate short visible wavelengths. They look just like dense cirrus but remember these are ~100km away from me at that camera elevation. What other cloud looks like that at that distance?!

[stefank]

Hi together,

what you see non the video mentioned is Airglow. Regarding the wavelength - near IR - it should be the Hydroxyl-Airglow layer which is located at a height of 86 - 87 km. It is like the mesosphere and the lower thermosphere under the influence of gravity waves that propagate from the troposphere up to 100 - 110 km.

Best regards,

Stefan

[Bill W]

Hi Stefan,

Yes, the Meinel bands are very bright in the 700-1000nm range. That was certainly providing the "background" to the IR observations I made a few years ago. If our eyes were sensitive to that range, they are so bright we might not be able to see the stars!
It's fascinating to watch the brightness change over time.

cheers,
Bill.