Expert explains the funnel-shaped vapor trail in the sky over Thanh Hóa
A strange streak of vapor stretching along the horizon over the former Hậu Lộc district was explained as being caused by aircraft engine exhaust.
Early on the morning of December 26, fishermen along the coast of Hậu Lộc, a former district in Thanh Hóa province in north-central Vietnam, and people in many other places spotted a bright white streak in the sky near the horizon. Many curious onlookers gathered to watch, taking photos and videos, and some believed it was a natural phenomenon heralding good fortune.
Residents of Hậu Lộc, Thanh Hóa filmed the vapor trail from an aircraft engine that they saw early in the morning. (Video: Provided by local residents)
According to Dr. Nguyễn Ngọc Huy, an expert in hydrometeorology and climate change, this is not a natural phenomenon. The funnel-shaped streak in the sky was produced by the engines of a jet aircraft.
Huy explained that when a slow-moving aircraft suddenly accelerates, it generates a powerful stream of compressed gas. When this exhaust is released into the air and meets the sudden cold of the surrounding environment, the rapid temperature difference causes water vapor to condense. This creates a trail of unusual shape, leading many people to think it is a natural phenomenon.
According to Huy, the shape of the trail comes from the hot engine exhaust propelling the aircraft in a horizontal funnel pattern, meaning air spreads outward from the center to both sides, producing a similarly shaped streak. The shape of the trail depends on how the aircraft's engines are operating.
The expert said that such trails form only when an aircraft suddenly speeds up or slows down in an area where the ambient temperature is low, at 0 degrees Celsius or below, and there is no strong wind.
A funnel-shaped vapor trail caused by aircraft engines. (Photo: Provided by local residents).
Sharing this view, Lê Đình Quyết, MSc, deputy head of the forecasting division at the Southern Regional Hydro-Meteorological Station, said the trail was very likely caused by a jet aircraft, since the cone-shaped head of the streak was moving. "This is not a natural phenomenon," Quyết said.
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