They are weird to say the least
"Polar mesospheric clouds (PMCs) or observed from the ground, this phenomenon is known as noctilucent clouds."
wiki " From satellites, PMCs are most frequently observed above 70°-75° in latitude and have a season of 60 to 80 days duration cantered about a peak which occurs about 20 days after the summer solstice. This holds true for both hemispheres. Great variability in scattering is observed from day-to-day and year-to- year, but averaging over large time and space scales reveals a basic underlying symmetry and pattern. The long- term behaviour of polar mesospheric cloud frequency has been found to vary inversely with solar activity."
They are best studied from space due to the unreliability in sightings from the ground. They are very hard to spot from the ground.
"They can be observed only when the Sun is below the horizon."
wiki Also confirming that the sun sets
below the horizon.

What your seeing from the ground

"When mesospheric clouds are viewed above the atmosphere, the geometrical limitations of observing from the ground are significantly reduced. They may be observed ‘edge-on’ against the comparatively dark sky background, even in full daylight."
wiki What you see from space
