Karl the Fog personification at Coit Tower

San Franciscans commonly personify the city's marine layer as 'Karl the Fog', a meme amplified by the popular Twitter account @karlthefog. Coit Tower on Telegraph Hill is frequently shrouded by this fog because of its exposed hilltop location. Locals and media often joke that 'Karl' lives in or visits Coit Tower when the structure disappears into fog. The tower is a prominent visual marker that frequently appears and disappears in these local jokes.