January 21, 1998 transcript #: 217-3
Subject(s): lights, swamp, oxidation
Title: WILL O’ THE WISP

The will of the wisp, often contracted to be pronounced ‘will o’ the wisp’, is a curious name for what are described by some as ghostly lights, a glow that drifts across swamps and marshes throughout the world. These lights have inspired images in people’s minds of fire breathing dragons, spirits and even UFO’s. Hi, I’m Dave Thurlow for The Weather Notebook, here to tell you about what’s also known as the swamp ghost phenomenon. This strange, swampy light is seen mostly in the warm south. The warmer it is year round, the more time there is each year for plants to grow, die and decay. The more decay, the more gas there is released into the swampy air. This is why many swamps - to put it delicately - stink. But it’s also why swampy air glows, or actually, burns! Swamp gasses, such as methane, as we all know, stink. But another gas released from decaying swamp matter, diphosphane, not only stinks when released to the air, it also very slowly catches on fire. The slow burning, or oxidation, of diphosphane causes the glowing light. But this is just the start of the process. The effect is enhanced by the weather. Nighttime weather, in the absence of any storms, is often calm and settled. Relatively cool night air tends to pool in low places like swamps. This cooling does two things that enhance the will o’ the wisp: it traps the gasses near the swamp, keeping them from being whisked away by the wind, and it makes fog, off of which the light of the burning gas reflects. You can hear, or read, a wonderful poem written in 1900 by Annie Campbell Heustis, called Will O’ The Wisp at our web site -- www.mountwashington.org. Support comes from Subaru, the beauty of all wheel drive and from the National Science Foundation.