1. A sinuous channel of very high ion density that propagates itself though a gas by continual establishment of an electron avalanche just ahead of its advancing tip. In lightning discharges, the stepped leader, dart leader, and return stroke all constitute special types of streamers. 2. See aurora. 3. A term used to describe a dropsonde observation when, because of either partial or complete parachute failure, the descent speed of the dropsonde exceeds 1500 feet per minute. 4. See snow trails.