Morning Glory Clouds Over Australia (2009 Aug 24)

apodman · Post by **apodman** » Mon Aug 24, 2009 4:18 am

http://antwrp.gsfc.nasa.gov/apod/ap090824.html

Nice picture, but ...

where's the astronomy? I've defended the choice of weather and atmospheric pictures before, even on flimsy grounds like "the air is what we look through to see the stars." But in this picture we're not even looking up toward the sky, we're looking down at the ground (and not from space, either). Neither is there a hint at an astronomical connection in the description. No optical effect caused by the clouds or atmosphere that has any relation to astronomical observation is shown nor mentioned. So I'd rather have an APOD that's really an APOD.

neufer · Post by **neufer** » Mon Aug 24, 2009 4:29 am

apodman wrote:http://antwrp.gsfc.nasa.gov/apod/ap090824.html

Nice picture, but ...where's the astronomy? I've defended the choice of weather and atmospheric pictures before, even on flimsy grounds like "the air is what we look through to see the stars." But in this picture we're not even looking up toward the sky, we're looking down at the ground (and not from space, either). Neither is there a hint at an astronomical connection in the description. No optical effect caused by the clouds or atmosphere that has any relation to astronomical observation is shown nor mentioned. So I'd rather have an APOD that's really an APOD.

--------------------------------------------
JULIET: It is some meteor that the sun exhales,
. To be to thee this night a torch-bearer,
--------------------------------------------
Meteor, n. [F. météore, Gr. , pl. things in the air, fr. high in air, raised off the ground; beyond + , , a suspension or hovering in the air, fr. to lift, raise up.] Any phenomenon or appearance in the atmosphere, as clouds, rain, hail, snow, etc.
--------------------------------------------
http://en.wikipedia.org/wiki/Morning_Glory_cloud
http://en.wikipedia.org/wiki/Arcus_cloud
http://www.youtube.com/watch?v=o5HFitSaPj4
http://www.youtube.com/watch?v=wW576V-8ZxQ
http://www.dropbears.com/brough/rollcloud.htm
--------------------------------------------

Qev · Post by **Qev** » Mon Aug 24, 2009 4:58 am

apodman wrote:http://antwrp.gsfc.nasa.gov/apod/ap090824.html

Nice picture, but ...

where's the astronomy? I've defended the choice of weather and atmospheric pictures before, even on flimsy grounds like "the air is what we look through to see the stars." But in this picture we're not even looking up toward the sky, we're looking down at the ground (and not from space, either).

Hey, Earth is a heavenly body too, yaknow.

apodman · Post by **apodman** » Mon Aug 24, 2009 5:14 am

the dictionary on my computer wrote:as-tron-o-my (uh stron'uh mee) n.
1. the science that deals with the material universe beyond the earth's atmosphere.

... and there's no definition 2.

http://en.wikipedia.org/wiki/Astronomy wrote:Astronomy (from the Greek words astron (ἄστρον), "star" and -nomy from nomos (νόμος), "law") is the scientific study of celestial objects (such as stars, planets, comets, and galaxies) and phenomena that originate outside the Earth's atmosphere.

So nice try, guys, but the first two sources I checked thought it was important to mention "beyond" and "originate outside" the Earth's atmosphere right off the bat. I'm going to pass on the opportunity to buy your arguments.

Did you know you can separate cosmic dust out of rain water and view it under a microscope to verify its origin? I can make an excuse for photographing a handful of dirt and calling it astronomy under the "originate outside" definition just like aurorae, so it's not like I'm closed-minded. Saying that photons from the Sun drive all weather phenomena gives almost anything a free pass, so strictly speaking I can't argue against purely weather topics, but it seems to me at some point we've crossed too many bridges from our original subject matter.

moonsighter · Post by **moonsighter** » Mon Aug 24, 2009 8:42 am

Greetings,

I have seen these same clouds when flying. But they were not real clouds. They were the vapor trails/chem trails from commercial aircraft. I know this because I saw one airliner go under us and there was the "cloud" forming right behind it, and because one airline goes along the same path in the sky there were several in a row just like the picture here. I saw several on that day in March over Germany-Holland.

geckzilla · Post by **geckzilla** » Mon Aug 24, 2009 11:01 am

License is misspelled in the credits at the top. Unless you are speaking Middle English... in which case, I guess everything else is misspelled.

Statistically speaking, astronomy picture of the day is still mostly astronomy picture of the day. Every now and then it's terrestrial picture of the day. But they can't change the name for that few percent.

@ chemtrails.

Storm_norm · Post by **Storm_norm** » Mon Aug 24, 2009 4:21 pm

could it be argued that the study of astronomy would almost imply that a foundation of knowledge of our initial surroundings (ie. some geography, some meteorology, topography, etc) at least be studied also?

what use is studying the sky if we don't also study our very own surroundings first? isn't it logical to get as much information about the earth in order to secure a fundamental foundation for everything else we see?

granted, the Earth cannot provide evidence of ALL phenomenon that goes on in our universe, let alone our solar system. but since we do live here, its a pretty good place to start our understanding of the Universe and Astronomy.

Also, it could be argued that true Astronomy would be the study of phenomena outside the influence of our own sun. When the discovery was made that the planets revolve around the sun along with the discovery that our galaxy is one of trillions, the concept of astronomy unwittingly took a fork in the road.

solar system astronomy - everything within the influence of the Sun and everything we can currently interact with. Therefore, everything we can interact with has a shape and size and contours and some have geography (atmosphere, weather, volcanoes, tectonics, craters, ) just as the Earth does.

and

Deep space astronomy - those things which we cannot currently interact with.

once that bridge is made and we are able to interact with things outside the influence of the Sun, then astronomy will take another fork in the road.

walfy · Post by **walfy** » Mon Aug 24, 2009 4:49 pm

When probes are on their way down to the surface of Saturn's moon Titan or our neighbor Mars, they take images looking down through the atmosphere and would surely qualify without quibble for inclusion on APOD. It makes no sense to exclude our own planet, from any perspective, at least occasionally.

Halberstadt · Post by **Halberstadt** » Mon Aug 24, 2009 8:01 pm

I am curious about the statement that these clouds can "achieve an airspeed of 60 kilometers per hour over a surface with little discernible wind." Exactly what is moving 60 KPH with respect to what? A thing which has an "airspeed" of 60 KPH is moving at that speed with respect to the surrounding air. Are the clouds moving fast through surrounding air? To state anything as an "airspeed... over a surface" seems wrong. Speed with respect to the earth's surface is "ground speed". Where is the "little discernible wind"? At ground level? Up where the clouds are? Inquiring minds want to know!

Bill Halberstadt

rigelan · Post by **rigelan** » Mon Aug 24, 2009 10:52 pm

apodman wrote:http://antwrp.gsfc.nasa.gov/apod/ap090824.html

Nice picture, but ...

where's the astronomy? I've defended the choice of weather and atmospheric pictures before, even on flimsy grounds like "the air is what we look through to see the stars." But in this picture we're not even looking up toward the sky, we're looking down at the ground (and not from space, either). Neither is there a hint at an astronomical connection in the description. No optical effect caused by the clouds or atmosphere that has any relation to astronomical observation is shown nor mentioned. So I'd rather have an APOD that's really an APOD.

I knew that would be the first post, I didn't know WHO would post it though.

orin stepanek · Post by **orin stepanek** » Tue Aug 25, 2009 3:55 am

http://images.flowers.vg/1024x768/morni ... whitea.jpg

I like morning glories as flowers. 8) I'm not sure what causes the roll clouds; but they are pretty impressive! Must take some pretty unusual weather conditions to form them; especially when they form several rolls like in the APOD.

Orin

DavidLeodis · Post by **DavidLeodis** » Tue Aug 25, 2009 12:53 pm

Fascinating cloud formation and image.

I'm curious though what the "Tip Thanks: James Holmes (Cairns)" in the credit means. Just what tip was given, presumably by James Holmes to Mick Petroff ? The "Cairns" is a link to the Cairns website but I could find no mention of a James Holmes in that site.

zbvhs · Post by **zbvhs** » Tue Aug 25, 2009 1:58 pm

Where's the astronomy?

Things like this fall under the category of planetary phenomena. If similar clouds had been observed on Mars, people would be falling all over themselves commenting on them with no issues. It's science in any case. Lay off the criticisms.

bystander · Post by **bystander** » Tue Aug 25, 2009 2:40 pm

DavidLeodis wrote:I'm curious though what the "Tip Thanks: James Holmes (Cairns)" in the credit means. Just what tip was given, presumably by James Holmes to Mick Petroff ? The "Cairns" is a link to the Cairns website but I could find no mention of a James Holmes in that site.

Don't know about the tip, but James Holmes is mentioned as part of the staff on the Cairns contacts page.

neufer · Post by **neufer** » Tue Aug 25, 2009 3:00 pm

Halberstadt wrote:I am curious about the statement that these clouds can "achieve an airspeed of 60 kilometers per hour over a surface with little discernible wind." Exactly what is moving 60 KPH with respect to what? A thing which has an "airspeed" of 60 KPH is moving at that speed with respect to the surrounding air. Are the clouds moving fast through surrounding air? To state anything as an "airspeed... over a surface" seems wrong. Speed with respect to the earth's surface is "ground speed". Where is the "little discernible wind"? At ground level? Up where the clouds are? Inquiring minds want to know!

Presumably these are basically gravity waves similar to ocean gravity waves that can

'achieve an "waterspeed" of 60 kilometers per hour over a ocean bottom
with little in the way of discernible water currents.'

bystander · Post by **bystander** » Tue Aug 25, 2009 3:16 pm

neufer wrote:Presumably these are basically gravity waves similar to ocean gravity waves that can
'achieve an "waterspeed" of 60 kilometers per hour over a ocean bottom
with little in the way of discernible water currents.'

But airspeed means with respect to the surrounding airmass, not the surface. Airspeed is higher with respect to ground speed if you are flying into the wind. That's why aircraft take off and land into the wind, lower ground speed for a given airspeed. I would measure "waterspeed" the same way, with respect to the surrounding water. It's not the same as ground speed, which is with respect to the surface.

DavidLeodis · Post by **DavidLeodis** » Tue Aug 25, 2009 4:37 pm

bystander wrote:
DavidLeodis wrote:I'm curious though what the "Tip Thanks: James Holmes (Cairns)" in the credit means. Just what tip was given, presumably by James Holmes to Mick Petroff ? The "Cairns" is a link to the Cairns website but I could find no mention of a James Holmes in that site.
Don't know about the tip, but James Holmes is mentioned as part of the staff on the Cairns contacts page.

Thanks bystander. Looking up the Cairn's staff email address list must have been the only place I did not look.

neufer · Post by **neufer** » Tue Aug 25, 2009 10:42 pm

bystander wrote:
neufer wrote:Presumably these are basically gravity waves similar to ocean gravity waves that can
'achieve an "waterspeed" of 60 kilometers per hour over a ocean bottom
with little in the way of discernible water currents.'
But airspeed means with respect to the surrounding airmass, not the surface. Airspeed is higher with respect to ground speed if you are flying into the wind. That's why aircraft take off and land into the wind, lower ground speed for a given airspeed. I would measure "waterspeed" the same way, with respect to the surrounding water. It's not the same as ground speed, which is with respect to the surface.

Your point is taken...the APOD is poorly worded.

Either "airspeed" or "speed over the ground" could have been used
but it was poor form to use both simultaneously.

walfy · Post by **walfy** » Wed Aug 26, 2009 1:47 am

How do these clouds form? Maybe it has to do with the temperature differences between the air above the ocean and the air above the land, considering these clouds form near the coast, if I understood correctly. Considering the hot Australian sun baking the land surface, then the way the heat is let off at night, that process might be very different than what's happening above the waters. Perhaps this causes an extreme difference in air temperatures in the air above the land and waters, separated by a very short distance, but many kilometers long and very straight, while the air on both sides stays very still. Then something gives it a nudge and one rolls into the other in a wave-like pattern, but due to the nearly-perfect straight line of the temperature boundary, caused by the coast, these wonderful clouds appear. But I'm not a scientist, just a thought that came to mind.

neufer · Post by **neufer** » Wed Aug 26, 2009 11:39 am

walfy wrote:How do these clouds form? Maybe it has to do with the temperature differences between the air above the ocean and the air above the land, considering these clouds form near the coast, if I understood correctly. Considering the hot Australian sun baking the land surface, then the way the heat is let off at night, that process might be very different than what's happening above the waters. Perhaps this causes an extreme difference in air temperatures in the air above the land and waters, separated by a very short distance, but many kilometers long and very straight, while the air on both sides stays very still. Then something gives it a nudge and one rolls into the other in a wave-like pattern, but due to the nearly-perfect straight line of the temperature boundary, caused by the coast, these wonderful clouds appear. But I'm not a scientist, just a thought that came to mind.

Dry air is more dense than moist air.

If cold morning dry air over land is overridden by a warm moist wind from over the ocean one might be able to generate a nice series of rapidly moving gravity waves in the heavy cold morning dry air.

The clouds would form from a thin rising warm moist air layer riding over the top of the cold dry air wave crests. The condensation heating of this thin layer cannot overcome the weight of the cold dry air wave crest below it or the weight of the overshooting warm moist air above it and gravity pulls it all back down.

mcbphx · Post by **mcbphx** » Thu Aug 27, 2009 6:17 am

I learned about the Morning Glory cloud phenomenon here.
http://cloudappreciationsociety.org/mg1/
The article is quite long, but its' worth a visit if only for the pictures. Quite remarkable, and their occurence is on a very large scale. The article includes details about sailplanes wave soaring ("surfing") in the updraft created by the cloud movement.

zbvhs · Post by **zbvhs** » Thu Aug 27, 2009 12:52 pm

The newspaper article was interesting and informative. I suspect the clouds are formed in the interface between a layer of cooler, dryer air overriding a warm, humid inversion layer. One clue is the way the doors of the beer coolers frost over as the clouds approach, which would happen if humidity increases (see the article). The land is apparently a broad flat coastal plain, so the overriding air would flow smoothly with very little disturbance. Mixing at the interface between layers would produce the rolling motion seen by observers. The clouds appear to have a faint spiral structure along their length, which might be caused by non-uniformities in the flow of overriding air. Interesting. Gulf of Carpenteria is probably one of the few places on Earth where these clouds would form.

bystander · Post by **bystander** » Thu Aug 27, 2009 1:22 pm

mcbphx wrote: http://cloudappreciationsociety.org/mg1/

Great article. Living in "Tornado Alley", I have seen roll clouds and shelf clouds, aplenty. Roll clouds are particularly impressive in the late afternoon. You can see a long stretch of white clouds, low to the horizon, rolling along the gust front of a rapidly building thunderstorm. You can actually watch the thunderstorm clouds build and the anvil tops form behind the roll. You know you are in for some severe weather. As with these "Morning Glory" clouds, strong winds usually precede the roll clouds, with an eerie calm behind them.

Star*Hopper · Post by **Star*Hopper** » Sun Aug 30, 2009 8:03 am

apodman wrote:http://antwrp.gsfc.nasa.gov/apod/ap090824.html

Nice picture, but ...

...

OK, I'll argue with ya. I don't even think it's a 'nice picture'. But I couldn't agree more with your message.

I'm afraid I'm in that "outside our atmosphere" boat.

I used to give lectures at our local planetarium before retiring, & in fact, used that classic definition during my introduction, in explaining the difference in 'astronomy' and 'astrology'. (And believe me, to too much of the lay population, it needs defining!) For those wondering about the other side of the equation, I basically dismissed the latter as "some kind of pseudo-science followed by fortunetellers & others without a firm grasp on reality, & usually as a means of profit."

Not saying the pictures aren't remarkable, and worthy of publication - but why not where the 'APOD' means 'Atmospherics Picture Of the Day'? But to avoid conflict & confusion, perhaps make it 'SPOD'....for 'Sky...' It could even be ran by the same staff - they've already got the facilities.

Not that it matters much - or enough - to anyone of importance, but I suffer an inner groan each time I start my every online day by opening APOD, like a child opening a Christmas or birthday present, eagerly anticipating what other-worldly delight each offering might present. And when I get the SPOD, I almost feel like we all did when it turned out to be just underwear or socks.

I've harbored a growing suspicion 'someone up there' or TPTB* have been feeling strapped for new material, given the number of times we've seen the same subject matter for an image, and an identical 'Explanation' caption, save a different word or two. (Look it up - use 'Search' for past APODs for a few, eg, NGC objects). Or perhaps that's just a sign of my advancing years? Not that I've 'seen it all' by any means, but APOD sometimes sure makes me feel that way!

*'The Powers That Be'

All this repetition, considering all the things 'out there' - kinda funny, innit? - how they turn to 'air pix' for filler material? EG today's image of bacteria in a Petri dish. Even the implication these might be cellular astronauts in some Weird Science Future didn't lessen the thoughts of something nasty, in my planetary nebula-wanting mind. Please. I couldn't restrain a snarky response (given elsewhere here) : "But can you make it fetch?"

But, fine - ok, & all that. Publish 'em if you must. Just.....not here?
Just sayin'....

~*

geckzilla · Post by **geckzilla** » Sun Aug 30, 2009 12:47 pm

I personally enjoy these loosely interpreted "astronomy" pictures. And given the choice between last year's random NGC I'd pick bacteria or roll clouds hands down. Good thing APOD isn't a democracy because if this thread is any indication then I'm in the minority.

Starship Asterisk*

Morning Glory Clouds Over Australia (2009 Aug 24)

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