This picture was taken last year overlooking Stockholm, Sweden. It shows the sun surrounded by a halo and two sundogs each one to the right or left of the sun. The halo and sundogs surrounding the sun are caused by the ice crystals created in the atmosphere. When ice crystals form in the atmosphere in hexagonal prisms, they can create these atmospheric events. Halos come from the way small ice crystals in the atmosphere scatter sunlight into different angles. The quality of a halo depends on the type and quality of the ice crystals that produce it. When these crystals flutter to the ground, they are mostly parallel to the ground with their faces flat. When this happens, each crystal can act like a lens, refracting the sunlight to form sundogs, also know as parhelia. The first halo seen around the sun is the 22 degree halo. The fainter second halo seen in the picture is the 46 degree halo which is rarer. These halos can also occur around the moon.
This was an interesting APOD because most of the time for me, I focus more on the events and objects that occur at night like the stars and moon. I have never really focused on the sun before, which is what we are currently learning about. Even though we have mentioned sundogs before in class, I was never sure what they looked like so it was pretty exciting to see this picture. It was also great to know that these events could occur with the moon. I have previously seen a moon halo before but I wasn't quite sure about the cause.
No comments:
Post a Comment