十万个为什么·科学阅读30篇（2）

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为什么有些火山喷发时会喷出蓝色火焰？

Blue flames occur when sulfur-rich gases ignite spontaneously upon contact with oxygen in cool air.
This happens most often at volcanoes like Indonesia’s Kawah Ijen, where sulfur deposits are abundant.
The combustion temperature exceeds 600°C, producing intense blue light visible even in daylight.
Unlike lava glow, blue fire emits no significant heat radiation detectable from afar.
Geologists measure gas composition using drones equipped with infrared spectrometers safely.
Local miners collect burning sulfur for industry, working near active blue-flame vents daily.
The phenomenon requires both high sulfur concentration and precise oxygen mixing ratios.
Volcanic lightning sometimes triggers ignition, but most flames burn steadily without sparks.
Scientists link blue flame frequency to magma degassing rates beneath the crater lake.
Monitoring flame color and intensity helps forecast explosive eruptions weeks in advance.