Have you ever heard someone say that it is ‘too cold for snow?’, and wondered if this was true. Our Science Correspondent Samantha looks at the science behind this claim.
Snow forms when the air temperature is low and there is enough moisture in the air to create tiny ice crystals. These crystals collide with each other and eventually clump together in clouds to become snowflakes.
When a snowflake becomes too heavy to remain in the cloud it falls to the ground. Snowflakes that fall through relatively dry, cool air will form a powdery kind of snow, while those that fall through air that is warmer and more moist will stick together to form a wetter kind of snow.
The idea that it could ever be too cold to snow is a myth but it is possible for conditions to be too dry for snow. It doesn’t matter how cold the air is, if there isn’t enough moisture for ice crystals to form then there will be no snow.
In Antarctica’s Dry Valleys, for example, the temperature has been known to drop as low as -68 Celsius, but it rarely snows; the air is too dry and any moisture that does begin to form is blown away by winds of up to 200 mph.
In contrast, the coldest place on Earth is believed to be on the East Antarctic Plateau, where it can be as cold as -93 Celsius but there’s plenty of snow.