Frost occurs more often in valleys than higher areas because cold air is dense and flows down valley slopes. When warm, moist air rapidly cools, tiny droplets of water may form and stay suspended in the air. This is fog. Fog is sometimes called low cloud. Warm sea breezes often produce fog when they move over colder land surfaces.
Fog is often thickest in valleys and low-lying areas.
Fact File Jack Frost is a fictional elf-like character, part of a Scandinavian legend. It is Jack Frost who is supposedly responsible for the patterns formed by frost. Resources and actions Teachers will need to ensure that there are no jagged edges on the can. Print off the student's worksheet and photocopy one for each student. Ask the students to carry out the activity from the worksheet then go over their results at the end of the class.