The story
Named for the tule wetlands of the Central Valley of California in the United States, where it forms.
Etymology from Wiktionary, CC BY-SA 4.0.
tule fog
Today it means: A thick, persistent ground fog, canonically found in parts of California's Central Valley, where cold air from the Sierra Nevada collects on the valley floor during the cooler part of the year and causes moisture to condense into fog or cold/freezing drizzle. Full definition →