1. NOTICE: The information contained within this document is copyright © U.S. Coast Guard Auxiliary No attempts to add, modify or delete information contained within this document shall be made. If errors are discovered, please contact the U.S. Coast Guard Auxiliary’s National Training Department.

2. Department of Training AUXILIARY WEATHER SPECIALTY COURSE INTRODUCTION AND CHAPTER ONE prepared by Weather Branch Copyright  2004 U.S. Coast Guard Auxiliary Association, Inc. Photo courtesy of National Oceanographic and Atmospheric Administration

3. ABOUT THIS COURSE PURPOSE Practical weather assessment Coastal patrols by Auxiliary vessels Train PE instructors SCOPE Basic principles of meteorology Physics without mathematics EACH LESSON COVERS ONE CHAPTER OV1-1 Copyright  2004 U.S. Coast Guard Auxiliary Association, Inc.

4. SYLLABUS Getting started (Lesson 1) Atmosphere properties and behavior (Lessons 2 – 4) Weather systems (Lesson 5) Internet weather products (Lesson 6) Forecasting methods and tips (Lesson 7) Coping with adverse weather (Lesson 8) OV1-2

5. NEWSPAPER WEATHER MAPS H H  CENTER OF HIGH PRESSURE L L  CENTER OF LOW PRESSURE FRONTS COLD WARM OCCLUDED STATIONARY JET STREAM OV1-3

6. MEASURING ATMOSPHERIC PRESSURE OV1-4 THE ANEROID BAROMETER SCALE IS ALSO CALIBRATED TO READ INCHES OF MERCURY INCHES OF MERCURY BAROMETER ANEROID BAROMETER VACUUM ANEROID BAROMETER VACUUM

7. THERMOMETERS OV1-5 50 40 30 60 50 40 30 60 BI-METAL STRIP BOILING POINT OF WATER 212 o F 100 o C FREEZING POINT OF WATER 32 o F 0 o C MERCURY OR ALCOHOL 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 FAHRENHEIT 0 10 20 30 40 50 60 70 80 90 100 CELSIUS LIQUID

8. HYGROMETERS HAIR EXPANDS OR CONTRACTS AS HUMIDITY CHANGES SCALE CALIBRATED IN “RELATIVE” HUMIDITY OV1-6 HAIR SPRING

9. ANEMOMETERS ROTATING CUP TYPEPROPELLER TYPE OV1-7 MEASURES WIND SPEED AND DIRECTION SHOULD BE MOUNTED 30 FEET HIGH IN A CLEAR AREA

10. WIND DIRECTION WIND BLOWS FROM A COMPASS DIRECTION WEST or WESTERLY NORTH or NORTHERLY SOUTH or SOUTHERLY EAST or EASTERLY OV1-8

11. CHANGES OF WIND DIRECTION WEATHER DETERIORATING WEATHER CLEARING COUNTER CLOCKWISE “BACKING” CLOCKWISE “VEERING” OV1-9

12. VISUAL OBSERVATION OF WIND OV1-10A DIRECTION AFFECTED BY BUILDINGS AND TREES SPEED OFFSHORE PROBABLY GREATER COASTAL WARNING DISPLAY SYSTEM

13. DAY NIGHT WARNINGWIND SPEED (KNOTS) UP TO 33SMALL CRAFT HURRICANE64 OR MORE STORM48 TO 63 GALE33 TO 47 OV1-10B

14. SURFACE650020000 CLASSIFICATION OF CLOUDS OV1-11 BY HEIGHT “FAMILIES” LOW (no prefix) MIDDLE “ALTO-” HIGH “CIRRO-” BY SHAPE “FORMS” CIRRUS ALTOSTRATUS CUMULUS ALTO  CUMULUS CIRRO  CUMULUS CIRROSTRATUS STRATUS

15. CLOUDS WITH EXTENSIVE VERTICAL DEVELOPMENT TOWERING CUMULUS WILL LIKELY GROW TO CUMULONIMBUS CUMULONIMBUS ARE THUNDERSTORM CLOUDS OV1-12

16. FRONT MILES 1,0005000 CIRRUS CIRROSTRATUS ALTOSTRATUS NIMBOSTRATUS STRATUS RAINFALL LIGHT TO MODERATE STEADY OR INTERMITTENT TYPICAL SPEED OF ADVANCE: 12 – 15 KNOTS OV1-13 TYPICAL CLOUD SEQUENCE AHEAD OF WARM FRONT

17. TYPICAL CLOUD SEQUENCE AHEAD OF COLD FRONT CIRRUS CIRROCUMULUS ALTOCUMULUS TOWERING CUMULUS CUMULUS CUMULONIMBUS MODERATE TO HEAVY SHOWERS TYPICAL SPEED OF ADVANCE: 20 – 30 KNOTS MILES 200150100500 FRONT OV1-14 SQUALL LINE CAN BE 50 TO 100 MILES AHEAD OF FRONT

18. VISUAL ESTIMATION OF CLOUD BASE HEIGHTS WITH ARM STRETCHED – FOUR FINGERS = 10 DEGREES OV1-15 10 o HEIGHT = 0.2 x DISTANCE USE KNOWN DISTANCE TO OBJECT UNDER CLOUD EDGE or ESTIMATED DISTANCE (25,000 FT) TO LOSS OF DETAIL

19. EXAMPLE USING LOSS OF DETAIL DETAIL SEEN HERE DETAIL DISAPPEARS HERE HEIGHT = 1 1 / 2 x 0.2 x 25,000 = 3,750 FEET WORKS BEST FOR LOW CLOUDS OV1-16 HORIZON ABOUT 1 1 / 2 HANDS

20. HEIGHT = 1,000 x (AIR TEMP. – DEW POINT TEMP.) ÷ 4.4 TEMPERATURES IN FAHRENHEIT HEIGHT IN FEET OV1-17 ESTIMATING CLOUD BASE HEIGHT FROM SURFACE TEMPERATURES EXAMPLE AIR TEMPERATURE = 81 o F DEW POINT TEMPERATURE = 70 o F HEIGHT = 1,000 x (81 – 70) ÷ 4.4 = 11,000 ÷ 4.4 = 2,500 FEET WORKS FOR CULUMUS AND ALTOCUMULUS CLOUDS DOES NOT WORK FOR STRATIFORM CLOUDS