1. A Quick Introduction to Clouds Lis Cohen liscohen@met.utah.edu www.WeatherOutreach.org

2. Cloud Naming Cloud naming is based on four cloud characteristics and three cloud levels There are about 30 distinct cloud types Professionals may use 10, a casual observer 3 or 4

3. Cloud Characteristics Cirrus – Fiber or Hair Cumulus –Heaped or Piled

4. Cloud Characteristics Stratus – Sheet or Layer Nimbus – Rain Making

5. Cloud Levels High Cumulus –Size of top of thumb at arms length Low Cumulus –Size of fist at arms length Photo: WBZ-Mos

6. Cloud Levels High Stratus –Sun and Moon easily seen Low Stratus –Sun and Moon difficult to see

7. Cloud Levels High Clouds Generally form above 20,000 feet Usually appear white, except for sunrise/set Usually thin and composed almost exclusively of ice crystals

8. Cloud Levels High Clouds Indicative of upper level moisture (storms possible in 6-24 hours).

9. Cloud Levels High Clouds CIRRUS CIRROSTRATUS CIRROCUMULUS Photo: WBZ-Mos

10. Cloud Levels Middle Clouds Cloud bases are located between 6,500-23,000 feet in the mid-latitudes Composed of water droplets and when temperatures are low enough, some ice crystals

11. Cloud Levels Middle Clouds ALTOSTRATUS ALTOCUMULUS

12. Possible marker of PM t-storms when seen in the AM with greater vertical development. (Clouds form in unstable air with stable air above them.) Cloud Levels Middle Clouds

13. Cloud Levels Low Clouds Cloud base lies below 6,500 feet Almost always composed of water droplets, but in cold weather, may contain ice particles and snow

14. Cloud Levels Low Clouds Stratus Stratocumulus Nimbostratus Museum of Science/WBZ conference

15. Cloud Levels Low Clouds Can form drizzle like precipitation Often stable layer is found above these clouds

16. Cloud Levels Large Vertical Development CUMULUS CUMULONIMBUS

17. Cumulus Humulis Cumulus Fractus Cloud Levels Large Vertical Development Photographer: Unknown

18. Cumulus Congestus Cumulonimbus Incus Cloud Levels Large Vertical Development Photographer: Unknown

19. Occurs with an unstable atmosphere Often indicative of thunderstorms and heavy rain Cloud Levels Large Vertical Development

20. Unique Clouds Lenticular Clouds Pileus Clouds Photographer: Unknown Photographer: Jay Shafer

21. Unique Clouds Mammatus Clouds Condensation Trail or Contrail Photographer: Unknown

22. Common Cloud Types

23. Description of Sky Conditions SUNNY OR CLEAR less than 1/10 sky covered by clouds PARTLY CLOUDY/ PARTLY SUNNY 1/10 to 5/10 of sky is covered by clouds

24. Description of Sky Conditions MOSTLY CLOUDY (MOSTLY SUNNY) 6/10 to 9/10 of sky is covered by clouds (sun) OVERCAST more than 9/10 of the sky is covered in clouds Undercast

25. Cloud Naming