Planning your shoot for the atmosphere

All the gear in the world doesn’t help if you ignore the sky you’re standing under – especially at night as I often do.

For example, in southern Alberta, we get a warm, dry wind that descends off the Rockies (a Chinook wind). When it arrives, a long band of clouds form along the foothills in front of of the Rockies and a strong wind pushes upper clouds eastward. It creates a clear band of sky in between the mountains and clouds over the prairies. The clear opening is known as a Chinook arch. A strong Chinook arch can stretch from Rocky Mountain house in the north, to the US border in the south (some 350km as the crow flies) and be 50-100km wide.

That movement creates immense turbulence as it flows over the mountains.

Under a Chinook, distance and geography matter

From the mountains near Canmore to the open prairies (Strathmore, Drumheller, Bassano, etc) it is roughly 150 kilometres measured in a straight line. Within that distance during a chinook event, fast-moving air can reach speeds capable of toppling semi-trucks – blowing your tripod over is a lot easier, so weight it or risk damage.

Depending on how strong the winds are, how wide the arch is, and the angle of the moon, sun, or stars I wish to capture, I might choose to position myself either right under it or well east of the foothills, under the clouds that are being pushed eastward. While under that cloud cover to the east, I could watch a Moonset or Sunset transit within the clear band to the west.

The right distance can work in our favour for three main reasons:

But, there are trade-offs…when the subject is low in the west, we are effectively shooting through a long horizontal column of fast moving air toward the mountains. Under a Chinook, that air can also be layered.

One of my usual goals is to capture images at wide, mid range, and zoom distances

Capturing dark sky views with three types of gear can be challenging, technically. Attempting all three simultaneously can be a true test of my skills, ha ha. But, with practice, images turn out a little better each time.

But not always.

While some images turn out crisp and clean, others are soft and hazy, almost dirty looking. Thanks – in most part – to the atmosphere or weather at the time.

Each of the three camera setups I described in my lunar eclipse article responds differently to the atmosphere. Let’s talk about how.

The 150–600mm magnifies air movement, especially for the moon and sun

The long lens is the most sensitive. At 600mm, subtle atmospheric instability shows up as shimmer or softness. For example, during a moon-set, when shutter speeds stretch past half a second, frame-to-frame sharpness can vary. This isn’t a focusing issue. It’s light passing through uneven layers of air across the distance. As the Moon or other target approaches the about 15 to 20 degrees altitude, contrast can fall off quite quickly.

The practical approach:

The 70–200mm turns atmosphere into character

At mid-range focal lengths, the same conditions feel different. Slight softness and colour shifts become mood rather than flaw. As the Moon or Sun lowers into thicker air: Reds can deepen. Edges soften slightly. The disk can take on a warmer glow. This lens often benefits from the Chinook setup, especially if the Moon descends toward the cloud boundary without entering it.

This setting sun drifted silently through the cloud layer, while the moon followed and hour later, hovering above the horizon. There’s no denying the mood – caused almost entirely by the atmosphere.

The wide lens benefits most from the arch

The 14–24 (set at 22-24mm) is least affected by subtle air distortion and most influenced by sky structure. A Chinook arch creates layers. Clear overhead. A defined cloud wall beyond. From a wide perspective, that separation adds depth and scale. If the Moon or sun sets toward that boundary, the composition gains a natural frame.

From a positioning standpoint, to capture the moon, stars, or sun transiting the clear sky band of a Chinook, you want:

Being a good distance east of the foothills is often a strong tactical position when dealing with a Chinook arch. Close enough to retain dramatic sky structure. Far enough to avoid the moon being swallowed by the clouds.

Under a Chinook arch, the challenge isn’t simply cloud cover, but distance and airflow. While that can reduce sharpness at long focal lengths late in the event, it also creates incredible drama and sky geometry that makes wider shots compelling.

Once we understand that balance, we can use it rather than fight it. Before we go, check out the atmosphere in these three images. While we can hope for th best, we should expect nature to do it’s thing.

Before you go…avoid frost and dew on your lens

A big part of any night shoot is keeping an eye on temperature and dew point. I often shoot in freezing weather, so I watch for frost on the lens, batteries losing charge, and temperature drops.

And don’t forget about radiative cooling…it can sneak up on you.

If frost or dew is likely, I bring both lens warmers and pocket warmers, and I keep spare batteries warm in my car or in my pockets. For long sessions, I pack a dummy battery so I can plug into a power brick or other power source.

And finally, bring snacks and drinks. You don’t want to be shooting for hours on end without properly fuelling your body. Especially if it’s cold.