1. Cirrus clouds are composed of ice crystals.

2. Cirrus clouds are usually forerunners of a cold front.

3. Scientists say the average cirrus cloud cover over the United States has increased 5 percent since the 1960s.

4. The sky is clear blue, with a few cirrus clouds adding texture to what looks like a flawless blue canvas.

5. He saw this splendidly illuminated cirrus cloud floating quickly on the wind while climbing one evening in the Buttermilk region of California's Eastern Sierra Nevada.

6. Suddenly, the cirrus cloud holding a still lake protrudes from the picture, as if a deep slit is torn on the background of noisy disorder.

7. It can be found that the highest frequency of cirrus cloud about 60% occurs in the south of China near the Intertropical Convergence Zone (ITCZ).

8. CALIOP cloud products are used to investigate spatial and temporal distribution characteristics of cirrus cloud over China.