⚓ THE GATE ⚓

The Fog

No discussion of the Golden Gate is complete without the fog.

The Science

• The fog that rolls through the Golden Gate is called 'advection fog' - formed when warm, moist Pacific air meets cold California Current waters.

• San Francisco's famous fog has a name: Karl. Named by an anonymous local, the moniker stuck and Karl now has his own Twitter account.

• The fog typically arrives in late afternoon, pouring through the Golden Gate like a slow-motion waterfall.

• International Orange was specifically chosen because it's highly visible in the fog while complementing the natural surroundings.

• The foggiest months are July and August, when the marine layer is thickest.

• The fog can reduce visibility to near zero, but the bridge's foghorns - which can be heard up to 4 miles away - guide ships safely through.

• The temperature difference between foggy San Francisco and sunny inland areas can be 30°F or more.

• Fog drip from the bridge cables can make the deck quite wet, even when it hasn't rained.

The Foghorns

The Golden Gate Bridge's foghorns are as iconic as the bridge itself.

• Sound: Two horns at the bridge's mid-span, one at each tower
• Range: Audible up to 4 miles away
• Frequency: The horns sound every 20 seconds during foggy conditions
• Purpose: Warning ships navigating the strait in low visibility

To San Franciscans, the foghorn's mournful call is the sound of home.

Fog Poetry

The Daily Drama

The fog's daily performance follows a predictable script:

1. Morning: Fog often blankets the city, especially in summer
2. Midday: Sun burns through, revealing the bridge
3. Afternoon: Heat inland creates low pressure, pulling marine air through the Gate
4. Evening: The fog returns, pouring through the strait like slow-motion water
5. Night: The foghorns sound; the bridge glows orange through the gray

This daily drama—sun and fog, reveal and conceal—is part of what makes the Golden Gate magical.