Exploring Kootenay Lake

Peter Bartl is a friend who lives on the high ground of Balfour. Knowing of my interest in things meteorological, he asked:

Although there are much lower snow depths elsewhere, the early-February snows of Peter Bartl's upper Balfour are deep.

Why do we … above Balfour, have so much more snow than everybody else along the West Arm … as you drive into Nelson, [there is] often no snow in spots along the way?

The short answer is that Balfour is exposed to southeasterly winds in a way that the rest of the West Arm is not.

Much of the heavy snow of winter arrives with the approach of cyclones—the travelling areas of low pressure that move over us from the west. That snow falls from the mid–levels of the atmosphere where it formed well above our mountain tops. If nothing else happens, that snow falls fairly uniformly across the region. But, something else does happen around Balfour—something that is different than elsewhere on the West Arm.

As a storm approaches, the low–level winds (below the mountain tops) are from the south to southeast, and as a map reveals, Balfour is open to those winds in a way that the rest of the Arm is not. As the air flows up the mountain slope above Balfour, low–level clouds form. Those clouds don’t actually produce much snow on their own, but they do greatly modify the snow from higher up as it falls through them. The snow from above grows quickly as it passes through those moisture–rich lower clouds. This produces considerably more snow for upper Balfour.

And there you have it: Balfour’s exposure to southeast winds produces low–level clouds that enhance the local snowfall well over that which falls elsewhere along the West Arm. The same explanation should apply to the Township of Queens Bay.

Who ever notices a mirage on the Lake?

Once I took pictures of mirages at the Coast and then included them in an article. A reader responded that everyday for years she went for a walk along the beach, but had never seen a mirage over the water. Now, as a result of  my article, she couldn’t stop seeing them; they abounded.

Mirages certainly abound on Kootenay Lake; few days are without them. And, I always find them fun to watch. So it was a couple of days ago during a walk at Kokanee Creek Provincial Park: I found myself admiring both the Purcells covered in snow and the Harrop ferry transformed by mirage.

The Kootenay-Lake Website offers more pictures and discussions of local mirages.

The first picture, below, shows the overview of the Purcells and the ferry. The second picture is an enlargement of the ferry. What looks as if a reflection, isn’t. Not only is the Lake too rough to give a simple reflection, but the lake surface cannot even be seen at the distance of the ferry. There is a slowly ascending optical surface (called a caustic), below which nothing—lake surface, ferry hull, distant beaches—can be seen. Objects which extend above the caustic are doubled: seen right way up, seen upside down. The ferry seems to float along through the air. This is an inferior mirage and the temperature difference between the air and water on this occasion was about 6°C.

Has the City of Nelson taken to imploring the Great Goddess of Weather to send no further snow for this winter? It might seem so: Arlene Anderson spotted this sign lying in the snow of Lakeside Park. Its message, to stay off the grass, is directed skyward.

Will Nelson’s supplication meet with success? It is the end of January; how much more snow might we normally expect to fall in the valleys?

The answer is offered by Discover Nelson which provides the annual snowfall data in this table. I added the column on the right: percent for the winter. It says that at the end of January, we have had about ¾ of the normal winter snowfall.

So, with only about ¼ of the winter’s snow left to fall, and that which is on the ground vanishing as the temperature rises, Parks may well come to believe that their entreaties were successful.

Of course, snowfall in the valleys is not the same as snowfall in the mountains. For for the latter, BC’s Ministry of the Environment offers insight. It posts regular updates to the snow pillow located high on Redfish Creek (altitude: 2086m). This large bladder contains pressure sensors to determine the weight of overlying snow. The results are then radioed to the Ministry and used to update the website.

The line for the multi–year average is purple. It peeks in early May at about 1400 mm of snow (water equivalent). At the end of January, the depth is about 800 mm, so nearly ½ the snow has yet to fall. This year’s plot is in dark blue and reveals this to be an average year.

While the Nelson data presents snowfall, the Redfish data presents snow depth—not quite the same thing for while the first climbs to a maximum, the second first climbs, but then falls. Nevertheless, both are informative.

But, the real question now is what happens if Nelson deems this experimental communication with the gods to have been a success? Might we expect to see more local signs imploring gods and goddesses. Maybe one in the August forest directed at Silvanus: No burning allowed. Or a zoning sign in May facing downwards under the bridge instructing nymphs and naiads: No high rises.

Maybe Nelson is on to something.

(Arlene Anderson’s picture is used with permission).

Meteorological optics have long been a passion of mine: rainbows, haloes, coronae, glories, sylvanshine, mirages, crepuscular rays, twilight, anti–twilight arch, the green flash, and many more. These are some of the things I have seen and photographed elsewhere. Alas, a number of these remain on my shopping list for this area. The glory had been one of the holdouts and so had not yet appeared on this markedly local website.

I realize that hikers and skiers will have often seen the glory around here, but my facility with such activities has declined of late. So, it was with great delight that I received a note from my friend (and wildlife consultant), Doug Thorburn, containing pictures he took of glories while he was skiing in the vicinity of Keen Creek.

The glory (yes, glory really is the technical name of this phenomenon) is often called the Brocken bow by climbers owing to a series of nineteenth–century observations of it from Brocken, the highest peak in the Harz mountains of Germany.

The glory appears as a series of coloured rings surrounding the anti–solar point (the point diametrically opposite the Sun). This is also the location of the head of the observer’s shadow, so an observer must be positioned such that his or her shadow falls on a cloud. Consequently, the glory is usually to be seen from a mountain or aircraft. When the cloud in which the glory is formed is quite close, the observer’s shadow on the cloud becomes visible to produce, what climbers sometime refer to as, the Brocken specter.

Despite the frigid look of these pictures, the glory is formed in clouds of water drops; clouds made of ice crystals will not produce it. It is explained by wave interference: light waves which exit a water drop after entering and reflecting off the back inside of the drop interfere with those which exit the other side of the drop.

Visit Play of Light on this website for links to many local illustrations of meteorological optics.

Doug Thorburn’s picture of a glory near Keen Creek. The glory is the nearly half circle of coloured light near the centre of the picture. He writes: “It was very cool coming up to a mountain pass and looking down the other side to see this.”

A second glory seen by Doug on his skiing trip.
Doug Thorburn’s pictures are used with permission.