ATM OCN 100 Summer ATM OCN Summer 2002 LECTURE 12 (con’t.) CLOUD OBSERVATIONS & CLASSIFICATION A. INTRODUCTION CLOUDS – SIGNPOSTS IN THE SKY B. CLOUD OBSERVATIONS & MEASUREMENTS C. CLOUD TYPES – CLOUD CLASSIFICATION SCHEME

ATM OCN 100 Summer Announcements u Homework 3 is: –Please Pick up yours in front (at end of class). –Key will be posted on the Web at: – u First Hour Exam –If you have not picked up exam, please do so! –An exam statistics page is posted at: u Did you forget to turn your clocks back 1 hour on Sunday?!

MADISON’S CURRENT WEATHER at 900 AM CST MON OCT Updated twice an hour at :05 and :25 Sky/Weather: MOSUNNY Temperature: 49 F (9 C) Dew Point: 36 F (2 C) Relative Humidity: 61% Wind: CALM MPH Barometer: 30.39R

ATM OCN 100 Summer CURRENT IR

ATM OCN 100 Summer CURRENT VISIBLE

ATM OCN 100 Summer CURRENT WATER VAPOR

ATM OCN 100 Summer Surface Weather Map from Today with Isobars & Fronts

ATM OCN 100 Summer Current Temperatures ( o F) & Isotherms

ATM OCN 100 Summer Current Dewpoints ( o F)

ATM OCN 100 Summer Current Precipitable Water (in mm) from GOES Satellites

ATM OCN 100 Summer Last 24 hrs in Madison

ATM OCN 100 Summer IFR – Instrument Flight Rules Red Dots: Ceiling < 1000 ft or Visibility < 3 miles

ATM OCN 100 Summer Tomorrow’s 7AM Forecast

MADISON’S CURRENT WEATHER Madison Weather at 1000 AM CDT 16 JUL 2002 Updated twice an hour at :05 and :25 Sky/Weather: SUNNY Temperature: 79 F (26 C) Dew Point: 60 F (15 C) Relative Humidity: 52% Wind: SW6 MPH Barometer: 30.13F ( mb)

ATM OCN 100 Summer Last 24 hrs in Madison FOG

ATM OCN 100 Summer CURRENT VISIBLE T.S. Arthur Winds: 60 mph

ATM OCN 100 Summer T.S. Arthur CURRENT IR

ATM OCN 100 Summer Yesterday’s High Temperatures ( ° F)

ATM OCN 100 Summer Current Surface Weather Map with Isobars (“iso” = equal & “bar” = weight), Fronts and Radar

ATM OCN 100 Summer Current Surface Winds with Streamlines & Isotachs (“iso” = equal & “tach” = speed) L L H H LL H H L L H L L H

ATM OCN 100 Summer Yesterday’s High Temperatures ( o F) – ( ) Average High Temperatures

ATM OCN 100 Summer Current Temperatures ( o F) – 24 Hrs Ago Cold Advection + Drier Air

ATM OCN 100 Summer Current Temperatures ( ° F) & Isotherms (“iso” = equal +”therm” = temperature)

ATM OCN 100 Summer Current Dewpoints ( o F)

ATM OCN 100 Summer IFR – Instrument Flight Rules Red Dots: Ceiling < 1000 ft or Visibility < 3 miles

ATM OCN 100 Summer Current Apparent Temperatures ( o F)

ATM OCN 100 Summer Forecast Heat Indices

ATM OCN 100 Summer Tomorrow AM Forecast Map

ATM OCN 100 Summer Announcements u Homework #3 is due next Thurs. 18 July 2002 u If you have ??, please see me.

ATM OCN 100 Summer ATM OCN Summer 2002 LECTURE 12 CLOUD OBSERVATIONS & CLASSIFICATION A. INTRODUCTION CLOUDS – SIGNPOSTS IN THE SKY – What can be learned from clouds? – Is it partly cloudy or partly sunny? – How are clouds classified?

ATM OCN 100 Summer CLOUDS - SIGNPOSTS IN THE SKY u Atmospheric moisture content; u Air temperatures aloft; u Atmospheric stability; u Tracer for winds aloft (speed & direction) and wind shear [speed/direction change with height].

ATM OCN 100 Summer B. OBSERVATIONAL MEASUREMENTS OF CLOUDS u Cloud Amount or Sky Cover – fraction of sky covered by a cloud; – based on visual estimates or measurements.

ATM OCN 100 Summer B. CLOUD OBSERVATIONS (con’t.) u Cloud Heights & Ceilings – Height of cloud base; – Based upon visual estimates or measurements.

ATM OCN 100 Summer C. CLOUD TYPES - CLOUD CLASSIFICATION SCHEME u Historical – Luke Howard in early 19th century. u Basis for Modern Traditional Cloud Classification Scheme – Appearance – Height

ATM OCN 100 Summer C. CLOUD CLASSIFICATION SCHEME (con’t.) u The Nature of Cloud Types – Layer or Stratiform Clouds F Layer forms indicate gentle uplift. – Heaped or Cumuliform Clouds F Puffy forms indicate vigorous uplift.

ATM OCN 100 Summer CLOUD TYPES [based upon International Cloud Atlas (WMO)] See Table 7.1 Moran & Morgan, 1997

ATM OCN 100 Summer HIGH CLOUDS > 20,000 ft (> 6 km) “Cold clouds” with ice crystals See Table 7.1 Moran & Morgan, 1997

ATM OCN 100 Summer Cirrus

39Cirrus

40 Cirrus

41 Cirrostratus

42 Cirrostratus (Cs) Made of a thin, transparent layer of (all ice) high clouds. Halos are common with this cloud type.

ATM OCN 100 Summer Cirrostratus

44 Cirrocumulus

45 Cirrocumulus

46 Cirrocumulus

47 Cirrocumulus (Cc) Note the clumpy rows – due to wind shear (also all ice)

ATM OCN 100 Summer MIDDLE CLOUDS 6500 to 20,000 ft (2 – 6 km) “Cold clouds” with supercooled water droplets See Table 7.1 Moran & Morgan, 1997

ATM OCN 100 Summer Altocumulus

50 Altocumulus (Ac) Remember…cumulus means puffy. (Can be a mix of ice & water)

ATM OCN 100 Summer Altocumulus

52 Altostratus

53 Altostratus

54 Altostratus

55 Altostratus (As) Another transparent layer….this one is at mid levels and can be made up of ice and water

ATM OCN 100 Summer LOW CLOUDS 0 – 6500 ft (0 – 2 km) “Warm clouds” with water droplets See Table 7.1 Moran & Morgan, 1997

ATM OCN 100 Summer Stratus

58 Stratus

59 Nimbostratus

60 Stratocumulus

61 Stratocumulus (Sc) (con’t.) Stratocumulus layers are thin, but can be extremely dense, as seen from above.

ATM OCN 100 Summer VERTICALLY DEVELOPED CLOUDS 0 – 10,000 ft ( 0 – 3 km) See Table 7.1 Moran & Morgan, 1997

ATM OCN 100 Summer Cumulus

64 Cumulus (Fair Weather) (Cu) Note the puffiness of the clouds. Also, they are rather isolated, although it may not appear that way on the horizon.

ATM OCN 100 Summer Cumulonimbus

66 Cumulonimbus

67 Cumulonimbus (Cb) Notice the anvil aloft! This cloud is probably nearly 100 miles away. They are huge!!! ANVIL RAIN SHAFT Approximate tropopause (~ 6 miles high)

ATM OCN 100 Summer Cumulonimbus

69 OTHER SPECIAL CLOUDS Cloud Species See Table 7.2 Moran & Morgan, 1997

ATM OCN 100 Summer Cumulus Congestus

ATM OCN 100 Summer Cumulus Congestus

ATM OCN 100 Summer Cumulus Congestus These may be seen in the early afternoon on a humid day. If so, Cumulonimbus will most likely form later in the day.

ATM OCN 100 Summer Mammatus

74 Altocumulus Lenticularis

ATM OCN 100 Summer Mountain Wave Clouds Fig Moran & Morgan (1997)

ATM OCN 100 Summer Mountain Cap Clouds Air can be lifted by the flow against a mountain to form these clouds.

ATM OCN 100 Summer Altocumulus Lenticularis

ATM OCN 100 Summer Contrails - Condensation Trail

ATM OCN 100 Summer Contrails – (9 Oct 2000 NASA)

ATM OCN 100 Summer C. CLOUD TYPES (con’t.) u Cloud Identification Aids – Texture – Cloud base estimation – Size of features – Shades of gray – Existence of optical phenomena u Gallery of Specific Cloud Types

ATM OCN 100 Summer D. CLOUD CLIMATOLOGY u Geographical variation of clouds u Seasonal variation of clouds

ATM OCN 100 Summer Average Cloudiness -- Annual

ATM OCN 100 Summer Average Cloudiness -- July

ATM OCN 100 Summer Average Cloudiness -- January

ATM OCN 100 Summer REVIEW of CLOUD TYPES [based upon International Cloud Atlas (WMO)] See Table 7.1 Moran & Morgan, 1997