A superb and very rare rainbow of fire appeared over Cluj, on Tuesday, April 2, at around 18.00. The phenomenon was photographed by a resident of Cluj above the village of Chinteni.
“It took about 2-3 minutes. It is an extremely spectacular phenomenon“, the Cluj resident told us.
Such a rainbow is extremely rare, not being a rainbow proper and having nothing to do with fire. More correctly, but less spectacularly, these would be called “circumorizontal arches”. Such a phenomenon was caught last year in China.
Circumhorizontal arcs occur when ice crystals in cirrostratus or cirrus clouds act as tiny floating prisms that refract sunlight into the color spectrum. The difference between this refraction and that of a rainbow is that, in the case of a rainbow, the light is refracted through water molecules and not through ice crystals.
Under what conditions does a fiery rainbow appear?
The phenomenon cannot be artificially induced. Perfect macro-meteorological conditions are needed for the formation of a “rainbow of fire”.
First, there must be cirrus or cirrostratus clouds. Next, the sun must be very high in the sky, at least 58 degrees above the horizon. Finally, the hexagonal ice crystals inside the clouds must be aligned horizontally to refract sunlight in a similar collective way.
When light enters through one vertical side face of such an ice crystal and exits through the lower one, it refracts or bends in the same way that light passes through a prism. When the crystals in a cirrus cloud are aligned just right, the entire section lights up in a spectrum of colors, according to National Geographic.
The phenomenon is similar to the iridescent clouds, also called “rainbow clouds” – sometimes they are also called “fire rainbows” – formed at the top of cumulus clouds after storms. They occur after air is rapidly pushed upward, causing it to cool and expand. Water droplets condense which can then act like prisms, forming a rainbow above the cumulus cloud.
Tags: Rainbow fire Cluj extremely rare phenomenon occur PHOTO
