96 terms

# RP 33, FLEET OCEANOGRAPHIC AND ACOUSTIC REFERENCE MANUAL

#### Terms in this set (...)

Speed of Sound in Air?
1100 fps / 4800 fps / 16000 fps
Define Snell's Law / HALT rule
Higher away Lower towards
What is the reduction of sound due to scattering and reflection?
Attenuation
What are the frequencies below 20 HZ, and above 20,000 HZ called?
Infrasonic and Ultrasonic
What has the most effect on sound velocity down to 1,000 FT?
Temperature
What has the most effect on sound velocity to 1,000 FT?
Pressure
What is Absorption?
Conversion of sound energy to heat
What is the range of noise produced by rain and hail squalls?
500-15000 HZ (occasionally as low as 100 Hz) (centered around 1Khz)
An isothermal condition will cause sound rays to do what?
Bend upwards
How many degrees in a time zone?
15 degrees
What is the formula for converting frequency to temperature?
(Freq-800 /20 = deg F)
What are the three types of Spreading and associated db loss?
Cylindrical-3db, Spherical -6db, Dipolar- 12db
How much depth excess is required for usable CZ?
200 fathoms, 22fps, 50%
How much depth excess is required for reliable CZ?
300 fathoms, 33fps, 80%
What is the East-West deviation of the earth's magnetic field called?
Magnetic variation
What is the average CZ range?
18-36 NM / MED 18-22 NM
What determines sonic layer depth?
Sound velocity
An increase in frequency will cause an increase in what?
Absorption
Attenuation caused by suspended particles in water is?
Scattering
The least seasonal temperature changes occur in what region?
Equatorial
What is a high-pressure area in a sound wave known as?
Compression
What is a low-pressure area in a sound wave known as?
Rare Fraction
What is the definition of a Frequency?
the number of wavelengths that occur in one second
What is the density of Saltwater?
64 lbs/cubic ft
What is the function of a hydrophone?
What is the emission of light by living organisms called?
Bioluminescence
At what depth have subs outlined with bioluminescence been detected?
250 ft
Where does the greatest seasonal sea surface temperature change occur?
Mid latitudes
What transmission occurs when sound rays in deep water are refracted then surface reflected?
CZ
What is the measurement of absorption of solar energy per unit area?
Intensity
What is the bending of sound rays due to variable consistencies?
Refraction
What condition is created when a -.2 degree gradiant occurs?
Isothermal
What is the loss of sound intensity due to Absorption and Scattering?
Attenuation
What will cause a reduction in salinity in the polar region?
Ice melt
All sound spreading starts with what?
Spherical
What initially affects a sonar ping?
Absorption
What type of noise does the sun produce?
Temporal
What is the primary factor affecting IRDS?
Moisture
Maximum sea state for a submarine to transfer?
SS-5
The Ocean bottom consist of what four main parts?
Continental Slope, Continental Shelf, Ridges, Abyssal
If you increase the acoustic intensity by 1000 times how many db have you gained?
30db
What is the November Index?
HF propagation -1-useless / 9-excellent
What is the Kilo index?
Temporal or Geomagnetic Noise ( variations in the earth's magnetic fields
When is the Deep Scattering Layer the shallowest?
Nighttime
What is RF energy is most affected by what?
Temperature
What is the most effect on spreading?
Distance
What does CAVU mean?
Ceiling and Visibility Unlimited
What is VATB?
Short form weather report (Visibility, Amount, Top of clouds, Base of clouds)
What is a Bowwave?
Long form weather report(Base, Top, Wind, Weather, Amount, Visibility, Extra)
What is shallow water?
100 Fathoms or less
In the Equatorial region, what is the predominate time for the Afternoon Effect?
1400-1500L
Where is the richest area of bioluminescence to occur?
Arabian Sea
What is the color of Bioluminescence?
Green or Blue
How many Gammas are at the Poles and at the Equator?
65,000 and 25,000
How long is the MAD index good for?
3 DAYS
100 ft in altitude equals how many Gammas?
1 GAMMA
What is the Speed of Light?
162,000 NM/Sec
What is a Radar Range Mile?
81,000 NM/Sec
How many Gammas equal an Orsted?
100,000 Gammas
What is the smallest form of Luminescent?
Bacteria
Convert 72 deg to Fahrenheit to Celsius?
22.2D Celsius
how long is the Alfa index good for?
72 HRS
What is the range for the Alfa index?
0-25
Alfa index disturbed?
25-50
50-400
Alfa index?
Unusable
What is absolute zero?
-273 Celsius
How much will a 100 ft of depth change the sound velocity?
1-7 fps
How much will a 1 degree in temperature change sound velocity?
4-8fps
How much will a 1/1000 ppt in salinity change sound velocity?
3-5fps
Define the Teaspoon Rule?
4800fps = 39 Deg F @ 35/1000 @ 0 ft
What water condition will cause the least absorption?
Smooth Sea Surface
What will scatter less sound, pebbles or sand?
Sand
How much do Gammas change in North - South travel?
-8Gammas/Degree
What are the three types of reverberation?
Surface, Bottom, and Volume
All sound starts as what transmission path?
Direct Path
How far can river run-off extend?
200 miles (upper 30 - 50 ft)
Thirty three feet in depth equals what?
1 Atmosphere
What percent of the sun's energy is absorbed with how many inches?
2 inches
What type of spreading will have the lowest loss and the greatest detection range?
Cylindrical
What percentage of sound radiated by submarines goes into bottom bounce?
87%
What bottom type will give the worst reflection?
Clay 20%
What will give the best bottom reflection?
Pebbles 70%
Whales are capable of making sound for what frequency?
50HZ
What are the two types of sound waves?
Transverse and Longitudinal
What are the dip angles at the poles and the equator?
90 - 0
What is Sub-refraction?
A curve away from the earth
What is Diffraction?
A bend around an object
What is Super-refraction?
A curve towards the earth
What is RF bending around an object?
Diffraction
What is IRDS measures in?
Microns
What type of water can give CZ?
If water depth is sufficient and DSC sound speed is at greater than near surface velocity.
What is turbidity?
Water with large quantities if clay, silt and in suspension.
Mad setting at 2.5, .8 gamma signal, what percentage of paper is signal?
32%
Wind being blown upwards away and replaced by air off the cool water is called?
Upwelling
What raypath has the longest detection ranges?
Isothermal