What is atmospheric pressure? The ocean of air that makes up our atmosphere is composed of gases, including nitrogen, oxygen, carbon dioxide and trace amounts of argon, helium and hydrogen. The ...

Heavy rain is hitting the Bay Area and coastal areas this week as an atmospheric river moves through Northern California.

Understanding atmospheric pressure is vital, newsroom meteorologist Justin Ballard said, because those giant H’s and L’s representing high and low air pressure systems on a weather map are ...