Can contrails forecast the weather?
Heather Kennedy of Bradford Ontario wants to know if the appearance and length of contrails tell you something about the coming weather. Contrails or condensation trails are long white streaks of ice crystals left behind in the exhaust of flying jet aircraft. At 8 to 12 km above the ground the jet engine pulls in very cold, dry air and spews out hot, water-filled exhaust. The hot water vapour mixes with the colder surrounding air. In doing so, it expands and freezes in 1 or 2 seconds forming a trail of ice-crystal clouds. Contrails do not cause weather, however, watching these contrails can provide a clue to upcoming weather. If a jet leaves no trail or a short trail or if the trail fades quickly, it is an indication that the air is relatively dry and sinking, which suggests that fair weather is likely to continue. On the other hand, if the exhaust trails linger for an hour or more or they spread across the entire sky, the surrounding air is probably moist and rising, foretelling the a
Contrails or condensation trails are long white streaks of ice crystals or tiny water droplets left behind in the exhaust of flying jet aircraft. At eight to 12 km above the ground, the jet engine pulls in very cold, dry air and spews out hot, water-filled exhaust. The water vapour in the exhaust mixes with the colder surrounding air and forms tiny water droplets or ice crystals. Contrails do not affect the weather. However, watching these contrails can provide a clue to upcoming weather. If a jet leaves no trail or a short trail, or if the trail fades quickly, it is an indication that the air is relatively dry and sinking, which suggests that fair weather is likely to continue. On the other hand, if the exhaust trails linger for an hour or more or they spread across the entire sky, the surrounding air is probably moist and rising, foretelling the arrival of a storm in a day or two. Reading contrails gives you a glimpse as to the weather over the next 12 to 24 hours.
