(1) The formation of wispy cirrus clouds is not a simple matter.

(2) Wispy cirrus clouds are the only ones that form naturally at the high altitudes where jets cruise.

(3) Over a distant horizon line, cirrus clouds fill the summer sky.

(4) The arc isn't a rainbow in the traditional sense - it is caused by light passing through wispy, high-altitude cirrus clouds.

(5) The persistent cirrus clouds indicate atmospheric turmoil at the levels where such control begins.

(6) The lowest of these clouds is nacreous, which normally forms between 10 and 20 miles above the Earth (compared with ice cloud cirrus at around 6 miles).

(7) High cirrus clouds form white streaks across its surface and a number of dark storms act as flaws and focus for the eye.

(8) Haloes can sometimes be a sign that rain is approaching, as cirrus clouds can mean that a frontal system is on its way.

(9) And from that perspective, you're looking at the very high cirrus clouds over the top of the storm.

(10) I lay on the bed and watched cirrus clouds drift slowly across the sky.

(11) In the troposphere, water exists as vapor in air, as liquid droplets in clouds, and as frozen ice particles in high altitude cirrus clouds.

(12) Cirrus clouds

(13) Above us the boundless blue sky was punctuated with a few fluffy cirrus clouds and the sun shining down on all of it.

(14) The purpose of the mission was to study cirrus clouds, to improve forecasts of future climate change.

(15) There have been few days without the presence of cirrus clouds.

(16) There were some high cirrus clouds earlier and it looks like they're coming back, but, for the most part, it's just been beautiful.

(17) A few cirrus clouds floated by, turning dark and blue around the edges.

(18) High, tropical cirrus clouds are made up of tiny ice crystals that float at altitudes from 20,000 feet to 60,000 feet.

(19) The basic cloud forms are cumulus, which are heaped clouds; stratus, which are layer clouds; and cirrus , which are wispy.

(20) Most halos appear as bright white rings but in some instances, the dispersion of light as it passes through ice crystals found in upper level cirrus clouds can cause a halo to have color.