What does a yellow sky during a storm mean?
A yellow sky during a storm is often an indicator of hail or severe weather. This yellow tint to the sky is caused by the sunlight reflecting off hail particles high up in the storm. The yellow-green color results from the combination of blue light dispersed by the water droplets mixed with the yellow light reflected by the hail. A yellow sky suggests the storm contains large hail and means there is strong updraft keeping the hail suspended in the thunderstorm.
Why Does Hail Cause the Sky to Turn Yellow?
Hail forms inside severe thunderstorms when strong updrafts carry water droplets high into extremely cold areas of the upper troposphere. As the supercooled droplets freeze into hailstones, they continue to grow as they bounce up and down through the cloud. Large hail over 1 inch across reflects more yellow light which makes the sky take on a yellowish or greenish cast when the sun shines on the hail-filled clouds. The more hail within the storm, the stronger the yellow-green coloration will appear.
Smaller water droplets scatter blue light preferentially, causing clear skies to appear blue. Larger hailstones reflect yellow as well, making the blue light and yellow light mix to create yellowish-green colored clouds. The yellow tint comes from the selective reflection and scattering of light by the ice crystals and water droplets of different sizes inside the storm clouds. More hail leads to more yellow light reflection, creating a yellow sky.
How Does a Yellow Sky Indicate Severe Weather?
A yellow-green sky is a telltale sign of large hail within a thunderstorm. For significant hail over 1 inch to form, the storm needs a strong updraft to keep the growing hail aloft long enough to reach large sizes. This is why yellow skies often indicate severe thunderstorms capable of producing damaging large hail.
The stronger the updraft, the larger hailstones can grow before falling out of the storm. Big hail requires a powerful updraft typically over 100 mph. These intense updrafts are the fuel that powers severe thunderstorms. So yellow skies are a visual clue that other hazards like high winds and heavy rain may accompany the large hail.
What Other Severe Weather Can Cause Yellow Skies?
While large hail is the most common cause, yellow skies can also be a sign of:
– Heavy rain – Dense rainfall can scatter yellow sunlight.
– High winds – Blowing dust or sand may contribute to yellow hues.
– Tornadoes – Twisting action and debris tossed in the air can color the sky yellow.
– Supercell storms – These rotating storms with intense updrafts breed large hail.
– Hail-producing cumulonimbus clouds – These towering “thunderheads” contain the strong updrafts that hail needs to grow.
So while hail is usually the culprit, a yellow-tinted sky often means more than just hail, but rather a whole cluster of storm threats.
What Should You Do if You See a Yellow Sky?
Here are smart steps to take if skies turn yellow during a storm:
– Seek shelter – Go indoors to a sturdy building away from windows. Basements or interior rooms offer the best protection.
– Avoid the storm’s path – If driving, turn around to get out of the storm’s way. Pull over if needed.
– Cover vehicles – Move cars into garages or put blankets over them to minimize hail damage.
– Alert others – Notify family and neighbors to take protective action immediately.
– Listen for warnings – Monitor weather alerts closely as conditions worsen.
– Remain vigilant – Stay alert even after the storm passes as new ones may develop.
– Document damage – Take photos of any property damage for insurance purposes after the severe weather clears.
How Long Do Yellow Storm Skies Last?
Yellow skies are a short-term phenomenon, typically lasting anywhere from 10 minutes to around 1 hour as the severe storm passes overhead. The sky returns to normal blue or gray coloring once the hail-producing section of the storm moves along. However, new storms may continue to develop as long as conditions remain unstable.
It is important to take quick protective action as soon as skies turn yellow. Do not wait for additional warnings. The yellow tint itself is advance notice that severe weather is imminent and precautions should be made immediately.
Conclusion
In summary, yellow skies accompanied by dark threatening clouds are Mother Nature’s way of signaling the presence of large, damaging hail and the likelihood of other hazards produced by severe thunderstorms. The intensity of the yellowish color reflects the size of the hail and severity of the approaching storm.
This useful visible cue should prompt quick precautionary action, as yellow skies mean a dangerous thunderstorm is on the horizon. Heeding the warning signs of yellow tinted clouds allows extra time to get to safety before the storm strikes. So the next time you see threatening clouds turned an ominous yellow hue, seek shelter right away!
| Hail Size | Adjective | Updraft Speed |
|---|---|---|
| 0.25 inch | Small | 20 mph |
| 0.75 inch | Penny size | 40 mph |
| 1.25 inch | Quarter size | 60 mph |
| 2 inch | Hen egg size | 80 mph |
| 2.75 inch | Tennis ball size | 100 mph |