Explanation:
What created this giant X in the clouds?
It was the shadow of
contrails illuminated from below.
When airplanes fly, humid
engine exhaust may form
water droplets that might freeze in Earth’s
cold upper atmosphere.
These persistent
streams of water and ice
scatter light from the
Sun
above and so appear
bright from below.
On rare occasions, though, when the Sun is near the horizon,
contrails can be lit from below.
These contrails cast long shadows upwards, shadows that usually go unseen unless there is a high cloud deck.
But that was just the case over
Istanbul,
Türkiye,
earlier this month.
Contrails occur all over
planet Earth and, generally,
warm the Earth when the trap
infrared light but cool the Earth
when they efficiently reflect
sunlight.
The image was taken by a surprised photographer
in the morning
on the way to work.