Rainbow – The Amazing Sky

July 20, 2014

Rainbow at Blackfoot Crossing

A low rainbow shines beneath a retreating thunderstorm at Blackfoot Crossing Historical Park.

On my way home from Waterton Lakes I drove through a thunderstorm, then watched it retreat and the Sun break through in the west. I was hoping for a rainbow in the east, and sure enough, one appeared.

With the Sun still high in the late afternoon sky, the rainbow was low, with just a small arc appearing above the horizon.

By good luck, I was passing the hilltop Blackfoot Crossing Historical Park, a beautiful museum interpreting the history of the Siksika Nation, and a great place to look out over the prairie.

These photos look down a line of rock cairns running from the interpretive centre to the hilltop cemetery in the distance, below the arc of the bow.

This wider angle image gives the context, with the bow at the bottom of the thundercloud, and fresh blue sky above.

I love the mountains but it’s nice to be back home on the prairies where we can see the wide horizon.

June 1, 2014June 1, 2014

Rainbow at Sunset

As the setting Sun broke through clouds it created a rainbow over my backyard.

I see lots of fine sky phenomena right from my back deck. Such was the case last evening as a storm retreated east as they typically do. Clearing skies in the west allowed the Sun to shine through, the perfect combination for a rainbow.

For the main image above I shot the double rainbow with the ultra-wide 14mm Rokinon lens …

… and also with the 8mm Sigma fish-eye lens for this image. It’s angled to be suitable for re-projection in a tilt-dome planetarium theatre.

We’re into stormy spring weather here in Alberta, so there will be many more rainbows to follow the dark clouds. Let’s hope for no more floods like last June.

December 11, 2013

The Colours of Iridescent Clouds

High clouds shimmer with iridescent colours near the Sun in an unusual display of atmospheric optics.

As I was getting ready to shoot the sunset at White Sands National Monument last evening, December 10, I looked up at the late afternoon Sun and saw it embedded in thin clouds tinted with iridescent colours. My dark sunglasses helped me see the phenomenon by eye, and underexposing the image helped me capture the colours by camera.

The effect is more common than you might think, but being so close to the blinding Sun iridescent clouds often go unnoticed. The almost metallic-looking colours are caused by clouds made of water droplets of such a uniform size they diffract the sunlight and spread the white light into a stunning range of colours.

This image frames the scene in portrait mode. I took several images over the few minutes the effect lasted. But the clouds soon moved off or changed structure and the iridescence faded. Despite the Sun shining through similar looking thin clouds the next evening, December 11, I saw no such iridescence.

For more information see Les Cowley’s excellent page at his Atmospheric Optics website.

It’s just another example of the wonderful phenomena of light and colour that the sky can present to the watchful.

November 10, 2013

Red Sky at Night … Sailor’s Delight

We saw many wonderful sunsets on our sail across the Atlantic, but this was one of the finest.

This was the sky two nights ago, on the evening of November 8, as the Sun, now below the horizon, lit up the clouds to the west. You can see a few people out in the netting of the bow sprit taking in the view.

Here was the view looking up into the square rigged sails on the foremast. “The sky is on fire” was the comment I heard from folks on deck.

Contributing to our theme of a rainbow eclipse trip, a red rainbow appeared to the east, lit by the light of the setting Sun. What a wonderful sky this was!

Indeed, one of the other astronomers on board tallied up the number of naked eye sky sights he had seen on the voyage. It was an impressive list, equalling what had previously taken him over 30 years of sky gazing to accumulate.

I’m writing this post from back on land, now in Barbados at a latitude of 13° north. However, now that I have high-speed connectivity I can get caught up with posts from the sea voyage, with a couple of more to come from at sea.

November 7, 2013November 19, 2013

The Rainbow Eclipse

For many of us on board the spv Star Flyer, last Sunday’s eclipse on the Atlantic Ocean will be remembered as much for the rainbows as for the eclipse.

The main image above shows the spectacular and classic double rainbow that appeared before the partial phases began, demonstrating the rain showers and unsettled weather we passed through on eclipse day.

The low rainbow shown here appeared well into the partial phase, with 60 to 70 % of the Sun covered, so the source of light is considerably smaller than usual for a rainbow. You can see multiple bands of colour on the inner edge of the inner bow. Seeing this appear and rushing over to shoot it was another exciting moment in a hectic morning of roller coaster emotions. As this bow appeared, the light was beginning to drop rapidly toward the final spectacle of totality.

July 5, 2013July 7, 2013

Low Bow over Canola

A horizon-hugging rainbow shines over a blooming field of canola.

You don’t often see a rainbow like this. Just the top of the bow pokes above the horizon and a field of yellow canola.

The reason is the Sun’s altitude. When I shot this in late afternoon yesterday, July 4, the Sun was 40 degrees up in the northwest. That means the point opposite the Sun was 40 degrees below the horizon in the southeast. Rainbows are centred on this anti-solar point and are always 42 degrees in radius. So doing the math shows that only the top 2 degrees of the rainbow arc could be visible above the horizon, creating a rainbow chord.

Later in the evening as another storm receded, a more classic bow appeared, this time as a double rainbow. With the Sun now much lower the anti-solar point was higher and more of the semi-circular bow appeared in the sky. I wish I could have shot a time-lapse of “rainbow rise” but downpours of rain prevented me from leaving the camera out.

These are neat examples of the play of light and colour in the open air. For lots more information, check out the wonderful Atmospheric Optics website.

June 3, 2012

Somewhere … Over the Rainbow

This wonderful rainbow lasted only a few minutes, as most do, shining in the brief interval when sunlight and raindrops are at their combined best.

I captured this rainbow off the back deck, on June 2, as a storm receded to the east and the Sun broke through in the west, ideal circumstances for catching a rainbow, at least photographically.

This was a classic bow, showing the inner main bow and the fainter outer secondary bow with colours reversed. The sky is bright inside the the inner bow from scattered light from the raindrops, and darker between the two bows where there is an absence of scattered light, a phenomenon called Alexander’s Dark Band after the ancient Greek astronomer who first described it.

I used a Canon 60Da and 10-22mm lens for this, at 10mm for wide-angle coverage of almost the entire rainbow.