When conditions are right, you might be lucky enough to one day see a “fogbow”. These ghostly-looking specters appear opposite the sun, just like a normal rainbow. But tiny water droplets in fog make them appear white, rather than colored when sunlight passes through them. They tend to appear in places prone to fog – like San Francisco. And you might also see them in the mountains of Romania, at the base of Yosemite Falls, or in the cloud forests of Costa Rica.