Enviromental Conditions Flashcards
If a wave length is 20m/66ft, what depth would a diver still be able to feel it?
10M/33ft
At what ratio of height to wave length does a wave break at?
Greater than 1:13
How can fog form?
1) When warm air blows over a cold surface.
2) When warm and cold ocean currents meet.
3) When warm sea air comes into contact with cold land, or vice versa.
Describe a ;
a)Cirrus cloud
B)Cumulus cloud
C) Stratus cloud
a) High streaky clouds
b) Heaped clouds
c) Layers or sheets of clouds
Describe;
a) Cumulo Nimbus
b) Nimbo stratus
c) Cirro cumulus
a) Large heaped clouds producing precipitation, the typical thunder cloud.
B) Continuous layer of grey cloud, steady rain.
c) High streaky clouds, starting to heap together.
What does
a) Nimbus mean?
b) Altum mean?
a) A cloud that produces precipitation
b) Meaning high
What is the difference between Spring and Neap tides
1) Spring tides are maximum tides, when sun and moon are aligned. Full moon and new moon.
2) Neap tides are are minimum tides, when the sun and moon are at 90deg to each other.
How long on average does a tide take to rise and fall?
6hrs, and 12 mins
What happens when the rising tide/flood tide reaches the top?
What happens when it lowers/ ebb tide reaches the bottom?
Remains constant for short period called “High Water Slack”.
Remains constant for short period called “Low water slack”
The twelfth rule is used to estimate the amount of rise and fall in each of the six hours.
What range would Hour 3 and 6 be?
Hour 1 1/12 of range Hour 2 2/12 of range Hour 3 3/12 of range Hour 4 3/12 of range Hour 5 2/12 of range Hour6 1/12 of range
What percentage of wind is generated in current?
If there is a Force 5, approx 22knots of wind,what surface current would this produce
a) 3% of the wind speed.
b) 0.6 knots of tide
When can diving from Mobile/portable diving craft. or any for of mobile diving be done?
What should it be equipped with?
Only in daylight, unless there is a suitable generator supplying lighting.
Must be equipped with normal marine emergency equipment of torches and flares etc
At what depth does a diver need to be provided with active heating of their gas supply?
150msw /660fsw
A surface supply diver, is diving on the bottom. What “should” be the max knots, if not pre planned?
1.5 knots
A diver is diving out of a bell/wet bell mid water. What “should” be the max knots he can dive if not pre planned?
1.8 knots
A diver is diving out of a bell/wet bell on the bottom. If not pre planned, what is the max current he can dive in?
2.0 knots beyond
A surface supplied diver, is mid water. If not pre planned, what is the max current he can dive in?
1.2 knots
What current can a mid water diver, dive up too routinely?
1.0 knot
A surface supply diver on the bottom can routinely dive in Currents up too?
1.2 knots
If a diver is diving out of a bell/wet bell, mid water. What is the max current he can routinely dive too?
1.5 knots
What is the max current a diver can routinely dive out of a bell/wet bell on the bottom?
1.8 knots
What is a Soliton?
A Soliiton is phenomenon, consisting of eddies, waves, or whirlpools which can occur at any depth.
“A self-reinforcing solitary wave”
(Wave packet or pulse)
What is the velocity of sound in water?
1,440 m/sec (3,240 mph)
Helmet diver are safe from any known sonar transmissions above?
500 Hz
A 3mm wet suit hooded diver has a protection between?
400-500 Hz at shallow depths <10 MSW
If a diver is stung or bitten subsea, what precautions should be taken?
Diver to be recovered to system or surface, to be monitored for observation. In case any signs of anaphylactic or toxic shock.
