Skills and the Diving Environment Flashcards
What causes Major Ocean Currents?
The rotation of the earth causes major Ocean Currents.
What causes tides?
The gravitational pull of the Sun and the Moon causes tides. The moon having a greater affect. Also topographical features in some circumstances.
In general, what is the best time to dive?
In general, it’s best to dive at the high tide or the slack period between high and low tides.
What causes waves?
Wind causes waves.
What causes a Longshore current?
Waves approaching the shore at a slight angle that push water down the shoreline result in longshore current.
What causes a Rip Current?
Waves pushing water over a long obstruction (ie, a reef), result in rip currents. The water cannot escape, so it funnels back to sea where there is an opening.
Which way do the major currents move in the northern hemisphere?
Major currents move clockwise in the northern hemisphere.
Which way do major currents move in the Southern hemishphere?
Major currents move anti-clockwise in the Southern hemishphere.
In which direction would the major ocean current travel on the East coast of a continent in the northern hemisphere?
The major ocean current travels South to North on the East Coast of the Northern Hemisphere.
Think it through! in the north, the current is clockwise, so would hit the east coast from the bottom and travel north.
What causes major ocean currents?
Wind and the Earth’s rotation causes major ocean currents.
What is the most accurate form of measurement underwater ( without using a measuring device)?
Arm Spans are the most accurate form of underwater measurement.
Imagine that you wanted to know the width of a wreck. You could be fairly accurate by using Arm Spans.
What should you consider when determining a search pattern to use for a lost object?
When determining a search pattern to use for a lost object you should consider the size of the object and the bottom topography.
In addition, the size of the search area and equipment available should be considered.
The generally preferred method for providing rescue breaths to a non-breathing diver at the surface is?
The generally preferred method for providing rescue breaths to a non-breathing diver at the surface is mouth to pocket mask.
What equipment is recommend for every diver to carry on a night dive?
Equipment is recommend for every diver to carry on a night dive is one primary light, a back up light and a chemical light.
On a night dive, each diver must at least have their own light.
What is the general size of capillary waves?
What is the general size of storm waves?
Capillary waves are very small in size.
Storm waves are large – 30 m + in size
The effects from waves stop at what depth?
The effects from waves stop at a depth of 45m.
What causes a wave to break?
When a wave is as deep as its height, bottom friction slows the forward speed, it bunches up becomes higher / steeper then breaks.
What causes a ripple affect on the sand running parallel to the shore, that can be used for natural navigation?
Waves and surge cause a ripple affect on the sand running parallel to the shore, that can be used for natural navigation.
How many times a day do the tides change?
Tides change twice daily.
What has the most effect on tides, the Sun or the Moon?
The moon has the most effect on tides.
