See what looks like a cliff behind the musher? This is a good example of what is called "Fata Morgana", also knows as a mirage. These are quite common here in the arctic.
The Fata Morgana is named after Morgan le Fay who was the shape shifting fairy half sister of King Arthur.
Wikipedia (The Source of all Wisdom and Knowledge) states:
"Fata Morgana is most common in polar regions, especially over large sheets of ice with a uniform low temperature, but it can be observed almost anywhere. While in polar regions Fata Morgana is observed on cold days, in deserts and over oceans and lakes Fata Morgana is observed on hot days. In this form of mirage, images which would normally be concealed behind the horizon appear distorted in the sky.
A fata morgana is caused by abrupt variances in air temperature; when air above the line of sight is warmer than the air below. This is known as temperature inversion, since it does not represent the normal temperature gradient of the atmosphere. Light traveling from the horizon is refracted towards the earth, away from the warmer air above. These are the conditions which cause a superior mirage - a Fata Morgana occurs only when light travels through multiple distinct temperature gradients. This results in an image which may be compressed in some sections and expanded in others. As air temperature changes over time so do the various angles of refraction, causing the image to expand or contract as the atmosphere returns to its standard temperature gradient."
There. You learn something new every day.