Quantum Rainbow.

Here's my take: The shaft of rain producing the rainbow isn't uniform across its width, but has 'holes' within the upper part of the shaft where the rain has stopped falling. At the edges of the shaft the rain is still falling through the vertical extent of the rainbow, but in the center it is not. If the shaft were uniform, the rainbow would extend all the way across its width, but in the top center the rain has stopped. What was falling in the center before it stopped is still descending and is producing the lower part of the rainbow. Moreover, even where the rain is still falling, its intensity varies. The rainbow is bright where the rain is falling with more intensity, and dimmer where the intensity is less. Where no rain is falling there is no rainbow.

My guess was that there was a strong wind event that temporally caused a rainless area. I thought the changes in the brightness might be due to cloud shadows.

Something that few realize about rainbows is that they are actually a circle, they only appear as and arc because the ground gets in the way. If you are in an aircraft flying through or near clouds you can some times see the full circle or at least more than you normally see on the ground.

Given that items like the ground can interrupt the circle of the rainbow there's no reason why a host of other items couldn't disrupt big chunks of it as well which is more than likely what we are seeing here.

I'm not 100% certain but I get the feeling that the size and distribution of the raindrops will vary the size, thickness and intensity of the rainbow. I haven't thought this through properly but I will over the next day or so and post what I come up with.

In the meantime I'm interested on what others think about it.

they only appear as and arc because the ground gets in the way

Do you mean that the unseen arc exists and we do not see it as ground gets in the way.... or

The full circle is not formed as ground gets in the way.

True, from airplane, we see full circle. (Even rarely we can see full circle wnen, sun is overhead and rains are there). But I think, full circle is not formed and only arc is developed as you can clearly identify the points on the ground, where the ends of arc touch

Don't necessarily need to be a 'high powered scientific type' to figure this one out. Any experienced storm chaser or spotter could come up with an explanation.

Without knowing much about the geography, which direction the camera was pointed, or a better view of the storm structure, I will hazard a guess. First clue is the rainshaft behind the rainbow. Most rainbows become visible when the observer is between the sun and the rain, and the rainshaft has recently passed over the area where the rainbow forms. From this, I believe the view is to the east.

The bright clouds right at the top of the lighthouse resemble the flanking line of a supercell, but I can not say for sure the storm is a supercell.

Supercell or not, the ragged appearance of the clouds indicate it is outflow dominant, and so it could be in the dissipation stage. In that case, what we are looking are the effects of downdrafts or outflow from a collapsing storm.

I wouldn't be surprised if a British stormchaser was on this one.

I'm sure the people at TORRO would like to see this one.

G'day gals, guys, gurus & Kris,

• we only get pumpkins in the shops at this time of year

I'd heard that and it's a great pity.

There are a whole raft of different pumpkins available in the shops in Australia year round and when cooked they produce a very sweet flavour. It may sound weird but you can actually use them in cakes and scones as a sweetening agent that replaces much of the sugar or other sweeteners. I have a recipe for pumpkin cake somewhere and from memory it's not dissimilar to banana cake but I can't be 100% sure of that. I've got no chance of finding my recipe but I will have a look on the net to see if anything jogs my memory.

Pumpkins are also really easy to grow yourself. Just keep some of the seed next time you have one and germinate them in a tray of moist cotton wool. Once they have germinated transplant them to seedling pots and then into the garden when they are large enough to survive outside. Be careful though, they are a ground dwelling vine and are extremely tenacious so if you allow them to get out of control they are almost impossible to get rid of. They also don't have a natural maximum size and will keep growing in size until they reach the limit of the vine that's feeding them with this little beauty coming in at 766 kg or a bit over three quarters of a ton.

However, like many fruits and vegetables each fruit has roughly the same amount of flavouring compounds so the bigger they are the more bland they become. As a result there has been a push to develop pigmy varieties that are about 20 to 40 mm in diameter that have extremely strong flavours.

G'day 3Doug ant others,

Having read what Doug had to say I think he has hit the nail right on the head.

The important factor here is the smudging, normally in a rainbow the controlling factor is the angle to the viewers line of sight. For the primary rainbow an angle of 40.6° produces the violet colour while red comes in at 42°. The following diagram comes from the Wikipedia article and shows how the rainbow is formed within the droplet of water through diffraction and total internal reflection.

Since the colours are smudged or blurred the question becomes what could cause the angles of each colour to change and the only thing I can think of is a change of the shape of the water droplets so they are no longer round. Normally a water droplet will fall to the ground with it's speed being inversely proportional to the size and while it's falling it will be pretty close to being spherical. However if the droplets were to be accelerated violently due to a sudden change in wind direction that you get with a microburst or as Doug calls them an outflow wind the shape would be distorted and give the sort of smudging you see in the original picture.

Good stuff Doug I've given you a thumbs up for your post.

This is a fascinating diversion masu, but.............ROFLMAO !!!!! I demand that Del hands over his record breaking off-topic post !

Sorry about that folks.

I find the CR4 editor a little wanting so I create and edit all my posts using Word. Then once I have finished composing it I cut it and paste it directly into the CR4 editor.

Somehow I managed to past two chunks that were destined for different discussions in the same post so my apologies.

Anyway, pumpkin soup is not only yummy but a healthy meal so I recommend indulging in a good old serve of it.

Perhaps you should backpedal a bit and rewrite the piece as "How Pumpkins Can Sweeten Any Rainbow" or something like that.

Well, on the other hand, maybe you shouldn't. With your luck it would prolly attract all those PerpMo's/GTU types lurking at The Fringe and, Lord knows, we've had quite enough of that.

Well, pumpkin bread and pumpkin soup are ideal fare when storm chasing and rainbow watching, so I guess it all fits, even if inadvertently. I'm thinking ice crystals, which have a different shape than water droplets, but the same basic effect on light, would account for such a smearing quite handily. A cold front isn't all that uncommon in the interior of a rain squall.

Thunderstorm clouds are not likely to have ice crystals. The insides of a thunderstorm are too dynamic for ice crystals to form, with strong updrafts and downdrafts, ambient winds that change speed and direction with height.

In prime storm chasing country (between the Rockies and the Ozarks), chasers usually rely on a chain of convenience stores known as Allsup's while out chasing. The typical fare is burritos and chips. Which might have something to do with Allsup's motto: Get Gas Here.

If a chaser has time, they might stop by a burger joint. A chaser is not likely to get a regular meal until after the chase.

Pumpkins, and sweeteners.

When my mom was younger she was a very good cook. She loved to bake pies with meals. Homemade pies with holiday meals were always looked forward to. Unfortunately as some of us age, the memory fails us at times. The last time my mom made Thanksgiving dinner for my family, she made a pumpkin pie for desert. She apparently forgot to add the sugar to the mix. My wife took the first bite, and was in shock, but proper manors prevented her from letting mom know of the error. Before my wife could decide what to do, my oldest daughter put a bite of pumpkin pie into her mouth. The look was shock. My wife caught her eye and motioned to her to not say anything. One at a time we all ate the pie, and said nothing. Mom and dad never had the pumpkin, choosing the apple instead. When we left that night I asked mom if I could take the pumpkin pie home with me. An hour's ride to the garbage can.

I later told dad of the sugarless pie. He told me that mom's memory was getting worse every day. Dad had helped her cook the food, but did not supervise the pies.

We miss mom now, but still laugh about her last pie.

It's really sad when that happens. My father is having a similar problem and even though the remote control for the cable TV have buttons shaped like arrows at least twice a day get asked which is the up, down, right, left and select buttons. But that's what family is all about.

Meanwhile the dogs have heard the answers to the questions about how to drive the remote control so often that I wouldn't be surprised if I found them channel surfing through the natural science programs one day.

Shadow lines in the photo do not support your theory though.

GA

Could a dense cloud have interrupted the sun's rays in that portion of the rain area?

Wikipedia has a fairly good article on rainbows that explains the optical mechanics behind them.

My take on it is that wind has displaced raindrops (ice particles can also show a rainbow, and this happens more often with ice than rain) causing a diffraction effect. The rainbow is a 2-D phenomenon in 3-D space, and with directional displacement that doesn't ruin the optics, you get this kind of concurrent spectral displacement.

Well obviously someone must have stolen a gold shilling from the pot of gold therefore disrupting the rainbow. Hopefully the shilling was returned before the leprechaun noticed.

A gold shilling? That I'd like to see!

As Masu said, rainbows are always circles or part thereof (due to the proximity of the ground). They always subtend the same angle to the eye and the phenomenon is caused by total internal reflection within raindrops. The theory is rather complicated - way beyond me.

I understand the type of phenomenon shown in the picture is probably caused by diffraction of the suns rays by ice crystals in the upper armoshere. The clouds make the colours visible by acting as a giant projector screen.

Tony Lee.

Flickr also had this ; http://www.flickr.com/photos/versevend/2578926204/

Could be a reflection from glass in the light house or a stranger yet refracted reflection; in a combination of the sunlight, the glass in the lighthouse an a single rain drop distorted by wind.