USCG AUX WEATHER
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Transcript of USCG AUX WEATHER
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.
Dep
art
men
t of
Tra
inin
g AUXILIARY WEATHER SPECIALTY COURSE
INTRODUCTION AND CHAPTER ONE
prepared byWeather Branch
Copyright 2004 U.S. Coast Guard Auxiliary Association, Inc.
Photo courtesy of National Oceanographic and Atmospheric Administration
ABOUT THIS COURSE
PURPOSEPractical weather assessmentCoastal patrols by Auxiliary vesselsTrain PE instructors
SCOPEBasic principles of meteorologyPhysics without mathematics
EACH LESSON COVERS ONE CHAPTER
OV1-1
Copyright 2004 U.S. Coast Guard Auxiliary Association, Inc.
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
NEWSPAPER WEATHER MAPS
HH CENTER OF HIGH PRESSURE
LL CENTER OF LOW PRESSURE
FRONTS
COLD WARM
OCCLUDEDSTATIONARY
JET STREAMOV1-3
MEASURING ATMOSPHERIC PRESSURE
OV1-4
THE ANEROID BAROMETER SCALEIS ALSO CALIBRATED TO READ
INCHES OF MERCURY
INCHES OFMERCURY
MERCURYBAROMETER
ANEROIDBAROMETER
VACUUM
ANEROIDBAROMETER
VACUUM
THERMOMETERS
OV1-5
50
40
30
60
50
40
30
60
BI-METALSTRIP
BOILING POINTOF WATER
212 oF100 oC
FREEZING POINTOF WATER
32 oF0 oC
MERCURY OR ALCOHOL
304050
60
70
8090
100110
120130
140
150
160
170180190
200
FA
HR
EN
HE
IT
0
10
20
30
40
50
60
70
80
90
100
CE
LS
IUS
LIQUID
HYGROMETERS
HAIR EXPANDS OR CONTRACTS AS HUMIDITY CHANGES
SCALE CALIBRATED IN “RELATIVE” HUMIDITY
OV1-6
HAIR
SPRING
ANEMOMETERS
ROTATING CUP TYPE PROPELLER TYPE
OV1-7
MEASURES WIND SPEED AND DIRECTION
SHOULD BE MOUNTED 30 FEET HIGH IN A CLEAR AREA
WIND DIRECTION
WIND BLOWS FROM A COMPASS DIRECTION
WEST orWESTERLY
NORTH orNORTHERLY
SOUTH orSOUTHERLY
EAST orEASTERLY
OV1-8
CHANGES OF WIND DIRECTION
WEATHERDETERIORATING
WEATHERCLEARING
COUNTERCLOCKWISE“BACKING”
CLOCKWISE“VEERING”
OV1-9
VISUAL OBSERVATION OF WIND
OV1-10A
DIRECTION AFFECTED BY BUILDINGS AND TREES
SPEED OFFSHORE PROBABLY GREATER
COASTAL WARNING DISPLAY SYSTEM
COASTAL WARNING DISPLAY SYSTEM
DAY NIGHT WARNING WIND SPEED (KNOTS)
UP TO 33SMALL CRAFT
HURRICANE 64 OR MORE
STORM 48 TO 63
GALE 33 TO 47
OV1-10B
SURFACE
6500
20000
CLASSIFICATION OF CLOUDS
OV1-11
BY
HE
IGH
T“F
AM
ILIE
S”
LOW
(no prefix)
MIDDLE “ALTO-”
HIGH “CIRRO-”
BY SHAPE“FORMS”
CIRRUS
ALTOSTRATUS
CUMULUS
ALTO CUMULUS
CIRRO CUMULUSCIRROSTRATUS
STRATUS
CLOUDS WITH EXTENSIVE VERTICAL DEVELOPMENT
TOWERING CUMULUS WILL LIKELY GROW TO CUMULONIMBUS
CUMULONIMBUS ARE THUNDERSTORM CLOUDS
OV1-12
FRONTMILES1,0005000
CIRRUS
CIRROSTRATUS
ALTOSTRATUS
NIMBOSTRATUSSTRATUS
RAINFALLLIGHT TO MODERATESTEADY OR INTERMITTENT
TYPICAL SPEED OF ADVANCE: 12 – 15 KNOTS
OV1-13
TYPICAL CLOUD SEQUENCE AHEAD OF WARM FRONT
TYPICAL CLOUD SEQUENCE AHEAD OF COLD FRONT
CIRRUS
CIRROCUMULUS
ALTOCUMULUS
TOWERING CUMULUS
CUMULUS
CUMULONIMBUS
MODERATE TO HEAVY SHOWERSTYPICAL SPEED OF ADVANCE: 20 – 30 KNOTS
MILES200150100500FRONT
OV1-14
SQUALL LINE CAN BE 50 TO 100 MILES AHEAD OF FRONT
VISUAL ESTIMATION OF CLOUD BASE HEIGHTS
WITH ARM STRETCHED – FOUR FINGERS = 10 DEGREES
OV1-15
10o
HEIGHT = 0.2 x DISTANCE
USE KNOWN DISTANCE TO OBJECT UNDER CLOUD EDGEor
ESTIMATED DISTANCE (25,000 FT) TO LOSS OF DETAIL
EXAMPLE USING LOSS OF DETAIL
DETAIL SEEN HEREDETAIL
DISAPPEARSHERE
HEIGHT = 11/2 x 0.2 x 25,000 = 3,750 FEET
WORKS BEST FOR LOW CLOUDS
OV1-16
HORIZON
ABOUT 11/2 HANDS
HEIGHT = 1,000 x (AIR TEMP. – DEW POINT TEMP.) ÷ 4.4
TEMPERATURES IN FAHRENHEIT
HEIGHT IN FEET
OV1-17
ESTIMATING CLOUD BASE HEIGHTFROM SURFACE TEMPERATURES
EXAMPLE
AIR TEMPERATURE = 81 oFDEW POINT TEMPERATURE = 70 oF
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