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How Thundersnow Works (and Where to Find It)
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olli...@gmail.com
Dec 22, 2019, 7:32:36 PM12/22/19
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How Thundersnow Works (and Where to Find It)
https://www.thoughtco.com/how-thundersnow-works-4159345
Quote--
Thundersnow is rare because the conditions that produce snow tend to have a stabilizing effect on the atmosphere. In the winter, the surface and lower troposphere are cold and have low dew points. This means there is little moisture or convection to lead to lightning. Lightning superheats the air, while the rapid cooling produces the sound waves we call thunder.
Thunderstorms can form in winter, but they have different characteristics. A typical normal thunderstorm consists of tall, narrow clouds that rise from a warm updraft leading from the surface up to around 40,000 feet. Thundersnow usually forms when layers of flat snow clouds develop instability and experience dynamic lifting. Three causes lead to the instability.
1. A normal thunderstorm at the edge of a warm or cold front can run into cold air, changing rain into freezing rain or snow.
2. Synoptic forcing, such as might be seen in an extratropical cyclone, can lead to thundersnow. The flat snow clouds become bumpy or develop what are called "turrets." Turrets rise about the clouds, making the top layer unstable. Turbulence causes water molecules or ice crystals to gain or lose electrons. When the electrical charge difference between two bodies becomes large enough, lightning occurs.
3. A cold air front passing over warmer water can produce thundersnow. This is the type of thundersnow most often seen near the Great Lakes or near and ocean.
Differences From a Normal Thunderstorm
The obvious difference between a typical thunderstorm and thundersnow is that a thunderstorm produces rain, while thundersnow is associated with snow. However, the thunder and lightning of thundersnow are different, too. Snow muffles sound, so thundersnow thunder sounds subdued and doesn't travel as far as it would in a clear or rainy sky. Normal thunder may be heard miles from its source, while thundersnow thunder tends to be restricted to a 2 to 3 mile (3.2 to 4.8 kilometer) radius from the lightning strike.
While thunder may be muted, lightning flashes are enhanced by reflective snow. Thundersnow lightning typically appears white or golden, rather than the usual blue or violet of thunderstorm lightning.
Thundersnow Hazards
The conditions that lead to thundersnow also lead to dangerously cold temperatures and poor visibility from blowing snow. Tropical force wind is possible. Thundersnow is most common with blizzards or severe winter storms.
Thundersnow lightning is more likely to have a positive electrical charge. The positive polarity lightning is more destructive than usual negative polarity lightning. Positive lightning may be up to ten times stronger than negative lightning, up to 300,000 amperes and one billion volts. Sometimes positive strikes occur over 25 miles away from the point of precipitation. Thundersnow lightning can cause a fire or damage a power line.
--End Quote
https://www.thoughtco.com/how-thundersnow-works-4159345
Quote--
Thundersnow is rare because the conditions that produce snow tend to have a stabilizing effect on the atmosphere. In the winter, the surface and lower troposphere are cold and have low dew points. This means there is little moisture or convection to lead to lightning. Lightning superheats the air, while the rapid cooling produces the sound waves we call thunder.
Thunderstorms can form in winter, but they have different characteristics. A typical normal thunderstorm consists of tall, narrow clouds that rise from a warm updraft leading from the surface up to around 40,000 feet. Thundersnow usually forms when layers of flat snow clouds develop instability and experience dynamic lifting. Three causes lead to the instability.
1. A normal thunderstorm at the edge of a warm or cold front can run into cold air, changing rain into freezing rain or snow.
2. Synoptic forcing, such as might be seen in an extratropical cyclone, can lead to thundersnow. The flat snow clouds become bumpy or develop what are called "turrets." Turrets rise about the clouds, making the top layer unstable. Turbulence causes water molecules or ice crystals to gain or lose electrons. When the electrical charge difference between two bodies becomes large enough, lightning occurs.
3. A cold air front passing over warmer water can produce thundersnow. This is the type of thundersnow most often seen near the Great Lakes or near and ocean.
Differences From a Normal Thunderstorm
The obvious difference between a typical thunderstorm and thundersnow is that a thunderstorm produces rain, while thundersnow is associated with snow. However, the thunder and lightning of thundersnow are different, too. Snow muffles sound, so thundersnow thunder sounds subdued and doesn't travel as far as it would in a clear or rainy sky. Normal thunder may be heard miles from its source, while thundersnow thunder tends to be restricted to a 2 to 3 mile (3.2 to 4.8 kilometer) radius from the lightning strike.
While thunder may be muted, lightning flashes are enhanced by reflective snow. Thundersnow lightning typically appears white or golden, rather than the usual blue or violet of thunderstorm lightning.
Thundersnow Hazards
The conditions that lead to thundersnow also lead to dangerously cold temperatures and poor visibility from blowing snow. Tropical force wind is possible. Thundersnow is most common with blizzards or severe winter storms.
Thundersnow lightning is more likely to have a positive electrical charge. The positive polarity lightning is more destructive than usual negative polarity lightning. Positive lightning may be up to ten times stronger than negative lightning, up to 300,000 amperes and one billion volts. Sometimes positive strikes occur over 25 miles away from the point of precipitation. Thundersnow lightning can cause a fire or damage a power line.
--End Quote
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