1. Ocean Physics Pressure, Buoyancy, Light and Sound

2. Ocean Physics Physical characteristics of the world ocean is determined by water’s properties of… Heat Capacity Heat Capacity Density Density Salinity Salinity & Ability to Transmit Light and Sound & Ability to Transmit Light and Sound

3. Thermostatic Properties   The Ocean has a thermal inertia: it resists change in temperature.   The poles receive less solar energy because the sun’s angle is further away, as compared to the tropics. The equator receives about 400% more solar energy than the poles.   Currents in the atmosphere and in the ocean move heat from the tropics to the poles. ex. Gulf Stream   Ocean currents and weather are a result of unequal solar heating. Heat transported by water vapor in atmosphere is greater than heat transported by water. Weather accounts for 2/3 poleward heat Ocean currents account for 1/3 poleward heat.

4. Light in the Ocean  Refraction - bending of light waves, magnifying objects  Refractive index - The amount light is refracted from one medium to the next The refractive index of seawater increases with salinity The refractive index of seawater increases with salinity

5. Light in the Ocean   Light is electromagnetic radiation that can have many wavelengths, other than just the visible spectrum.   Only green and blue wavelengths pass through water at any appreciable depths and quantities. The ocean is the color it is because those colors are not absorbed but reflected back to you.   As you go deeper, all colors are absorbed except for blue and green. At 33 ft down, red appears gray. Underwater pictures appear their true color because a light source is used.   Water color can also be a result of sediment, organisms (or lack there of), pollution or chemistry of water.

6. Sound in the Ocean   Sound can travel great distances and is 4-5x faster in water   Speed of sound is faster in high temperatures and pressure.   Sound is fastest at the surface and very deep. Loud noises at deep depths (sound channel) can be heard for thousands of km.   Sound bounces off the thermocline to produce an area of poor sound transmission known as the shadow zone (submarines hide here)

7. Equipment   Hydrometer ratio of the density of the liquid to the density of water   Calorimeter measures heat capacity   pH meter/probe Measures pH   Osmometer measures osmotic pressure   Nansen bottle salinity measured at different depths bottle is sent down upside down on a string, flipped open at a desired depth, and a sample of water is taken   Salinometer electronic electricity conductor   Refractometer measures salinity by the degree the light is bent

8. PRESSURE

9. What Causes Pressure?  Pressure in the ocean is determined by: The weight of the water pushing down on the object (measured in pounds) The weight of the water pushing down on the object (measured in pounds) The size of the surface (surface area) the water is pressing against (measured in square inches) The size of the surface (surface area) the water is pressing against (measured in square inches)

10. HOW IS PRESSURE MEASURED?   Scientists measure pressure in units called bars. ATM=Atmospheric pressure or atmospheres…1 atm= 1 bar   One bar equals 14.7 pounds per square inch (psi) of pressure.   At sea level, the weight of the atmosphere exerts a pressure of about one bar. This means that 14.7 psi of pressure are pushing down on our bodies as we rest at sea level. Our body compensates for this weight by pushing out with the same force.

11. WHAT IS PRESSURE?   Since water is much heavier than air, this pressure increases as we venture into the water.   Underwater, pressure increases by one bar for every 33 feet (10 meters) increase in depth. This pressure is caused from the weight of the water. This means that at 230 feet, the total pressure is eight bars, or eight atmospheres (eight times the surface pressure). (230 ÷ 33 = 8 bars) (8 bars x 14.7 = 117.6 psi)

12. Pressure Calculations What is the ocean pressure at 330 ft in bars? 330 divided by 33 = 10 bars How much is this in psi? 10 bars x 14.7 psi = 147 psi What is the pressure at 4920 ft? 4920 divided by 33 = 149 bars How much is this in psi? 149 bars x 14.7 psi = 2190.3 psi

13. CALCULATE PRESSURE   You are 66 ft underwater: How many bars? 2 bars (66 / 33 = 2) How many psi? 29.4 psi ( 2 bars x 14.7 psi = 29.4)   You are 99 ft. underwater: How many bars? 3 bars (99 / 33 = 3) How many psi? 44.1 psi ( 3 bars x 14.7 psi = 44.1)

14. IMPACT ON HUMAN EXPLORATION   This pressure increase poses a serious challenge to human exploration of the oceans.   In fact, the deep parts of the oceans are relatively unexplored, as compared to the rest of the planet.   Recreational diving, is any depth around 30 meters (98 ft) but this depth is also where nitrogen narcosis becomes a hazard..   Anything from 60ft to 100ft is considered a “deep dive”.   Scuba divers can reach around 130 ft – 330 ft… recommended maximum depth for Technical divers.. Some have tried to go further… 384 was first thought as the max… there was one diver recorded up to 500 ft with compressed air…deepest ever SCUBA dive was 1,089 ft. Egyptian diver Ahmed Gabr has the official world record for the deepest scuba dive: 332.35 meters (1090.39 ft).. Got there in 12 minutes, but took 14 hours to resurface to avoid sickness.   US Navy divers use an atmospheric diving suit which allows very deep dives of up to 700 meters (2,300ft). These suits are capable of withstanding the pressure at great depth permitting the diver to remain at normal atmospheric pressure.

15. 64 lbs Water doesn’t change density under pressure Water is uncompressible. This means that water under great pressure (force per area) will have the same volume as water under much less pressure. http://www.unmuseum.org/concrete.htm

16. How do divers combat pressure?   Divers going into the ocean have to breathe pressurized air or other gas mixtures. This can cause problems in itself, however, because of excess gas in the body tissues. This limits the depths that humans are capable of diving to.   As divers make their way back to the surface, they sometimes must make timed stops to release excess gas.   If they arise too quickly, a condition called “bends” can occur. After working underwater for hours at a time, professional divers undergo routine controlled decompressions in a special pressure chamber. These chambers are also used to treat pressure-related diving illnesses, including “bends”.

17. Pressure and Exploration  Pressure increases with depth  Humans are only capable of traveling to a certain ocean depth Gases build in the body tissues Gases build in the body tissues Bends (decompression sickness) can occur if they come up too quickly Bends (decompression sickness) can occur if they come up too quickly

18. BENDS  CAUSED BY THE FORMATION OF BUBBLES OF GAS THAT OCCUR WITH CHANGES IN PRESSURE DURING SCUBA DIVING.  DISSOLVED GASSES (MAINLY NITROGEN) COME OUT OF SOLUTION IN BUBBLES AND CAN AFFECT JUST ABOUT ANY BODY AREA INCLUDING JOINTS, LUNG, HEART, SKIN AND BRAIN TISSUES.

19. Marianas Trench  The deepest part of the world’s oceans.  The deepest part of this trench is called the Challenger Deep, -a valley located in it’s ocean floor off the coast of Japan.  It measures 35,797 feet deep!  The pressure is 8 tons psi. This is equal to the weight of about 48 Boeing 747 jets. This is equal to the weight of about 48 Boeing 747 jets.  Invertebrates, such as starfish and tube worms, thrive here!

20. 11000 meters = 36,089.24 feet = about 6.8 miles

21.  James Cameron’s exploration into Mariana’s Trench http://video.nationalgeographic.com/video/ne ws/deep-sea-challenge/cameron-how-deep http://video.nationalgeographic.com/video/ne ws/deep-sea-challenge/cameron-how-deep http://video.nationalgeographic.com/video/ne ws/deep-sea-challenge/cameron-how-deep http://video.nationalgeographic.com/video/ne ws/deep-sea-challenge/cameron-how-deep  Documentary of Mariana’s Trench http://www.youtube.com/watch?v=W2qdlYkl2 HY http://www.youtube.com/watch?v=W2qdlYkl2 HY http://www.youtube.com/watch?v=W2qdlYkl2 HY http://www.youtube.com/watch?v=W2qdlYkl2 HY https://www.youtube.com/watch?v=uz73TbB2 Sxo https://www.youtube.com/watch?v=uz73TbB2 Sxo https://www.youtube.com/watch?v=uz73TbB2 Sxo https://www.youtube.com/watch?v=uz73TbB2 Sxo

22. SCUBA S – Self C – Contained U – Underwater B – Breathing A – Apparatus Aka – breathing air from a compressed air tank.

23. Pascal’s Principle Pressure applied to fluids is equally transmitted in all directions, to all parts of the fluid and to all parts of a container. Pressure applied to fluids is equally transmitted in all directions, to all parts of the fluid and to all parts of a container. Think toothpaste… Think toothpaste…

24. Pascal’s principle = a fluid distributes the force in all directions equally

25. Hydraulic (fluid) brakes… (GUY STUFF… SNOOZE…)

26. Henry’s Law When a mixture of gas is in contact w/a liquid, each gas will dissolve in the liquid in proportion to its partial pressure. Gasses can go in and out of solution e.g., open soda, get CO 2 bubbles (CO 2 is under pressure)

27. The problem of breathing compressed air: Nitrogen gas: - Starts at 30m (90ft) - Feels like intoxication - Causes death most commonly because of stupid choices, just like alcohol. Oxygen gas: - Much more serious starts at deeper levels - Most common with mixed gases with high levels of oxygen - Effects are not as reversible - Brain damage, blindness, convulsions… bad stuff Both oxygen and nitrogen are toxic if you breathe them under pressure!!!!

28. Mixed gases Normal air is what most SCUBA uses, but to go deeper you must mess with the mix of air you breath down there Air up here is 21% oxygen 70% nitrogen 9 % various other gases Diving deep often requires mixes other Than these %’s

29. But the view is amazing

30. HOW DO ANIMALS COMBAT PRESSURE   Aquatic animals have various ways to adapt to varying pressures on their bodies.   They usually undergo large pressure changes in short amounts of time.   Fish that live in shallower waters usually have swim bladders filled with air, to help them stay afloat in shallow waters.   Fish living in deeper parts of the ocean, however, usually have body cavities filled with fluid, rather than air.   Some aquatic organisms, like sharks, have livers containing oil to help them live in mid-depths. Sharks tend to travel in shallower water to feed, then head back to deeper waters for camoflauge.

31. FUN FACT….   Sperm whales make hour-long dives 7,320 ft down.   This is a pressure change of more than 223 bars!   By studying and understanding how these animals are able to withstand great pressure changes, scientists will be able to build better tools for humans to make such journeys.

32. Decompression Sickness As they descend into the water, the external pressure increases proportionally to the depth. The compressed air that is breathed is equal in pressure to that of the surrounding water. The longer a diver stays down and the deeper the dive, the more compressed gas that is absorbed by the body. When the diver ascends, time must be allowed for the additional gases to be expelled slowly or they will form bubbles in the tissues. This gas is N 2, it will enter the blood circulation When extra N 2 leaves the tissues, large bubbles form. N 2 bubbles can travel throughout the system and into the lungs and blood routes. This N2 gas build up can cause paralysis and convulsions (divers’ palsy), difficulties with muscle coordination and sensory abnormalities (divers’ staggers), numbness, nausea, speech defects, and personality changes

33. Treatment: Hyperbaric Chamber

34. HYPERBARIC CHAMBER  Also called decompression chamber or recompression chamber  Sealed chamber in which a high-pressure environment is used primarily to treat decompression sickness, gas embolism, carbon monoxide poisoning, gas gangrene resulting from infection by anaerobic bacteria, tissue injury arising from radiation therapy for cancer, and wounds that are difficult to heal.  oxygen is pumped in by a compressor or allowed to enter from pressurized tanks.  Pressures used for medical treatment are usually 1.5 to 3 times ordinary atmospheric pressure.

35. Buoyancy  Buoyancy is what determines whether an object will float or sink when it is put into water.  Something that is less dense than water will float, while something that is more dense than water will sink. You can figure out the density of an object by taking that object's mass and dividing it by its volume. Fresh water has a density of 1 (gram/cubic centimeter), while salt water is slightly more dense. You can figure out the density of an object by taking that object's mass and dividing it by its volume. Fresh water has a density of 1 (gram/cubic centimeter), while salt water is slightly more dense.  When scuba divers go underwater, they want to become neutrally buoyant, which means they are neither sinking nor floating.  Divers are able to achieve neutral buoyancy using two devices: Weight Belt. Divers use a very dense weight belt to help counteract their natural tendency to float. Weight Belt. Divers use a very dense weight belt to help counteract their natural tendency to float. Buoyancy Compensator (BC). A device that can add air if needed to help make the diver more buoyant. Buoyancy Compensator (BC). A device that can add air if needed to help make the diver more buoyant.

36. Maintaining “neutral” buoyancy is tricky 1) Positive buoyancy = floating 2) Negative buoyancy = sinking 3) Neutral buoyancy = suspended … not going up or down It is very important for a diver to reach neutral buoyancy. It is very important for a diver to reach neutral buoyancy. If they are not dense enough, they will rise back to the surface. If they are too dense, they will fall to the ocean floor, possibly crushing things like fragile coral reefs in the process. If they are not dense enough, they will rise back to the surface. If they are too dense, they will fall to the ocean floor, possibly crushing things like fragile coral reefs in the process.

37. Buoyancy and Floating  If the total area of the object that makes contact with the water is large enough, it will float  The volume of water pushing against the object must equal the volume of water that is displaced by the object  The object’s weight, or density, is also a determining factor

38. BUOYANCY   The object must make room for its own volume by pushing aside, or displacing, an equivalent (or equal) volume of liquid.   The object is exerting a downward force on the water and the water is therefore exerting an upward force on the object.   Of course the floating object's weight, (and density) comes into play also.   The solid body floats when it has displaced just enough water to equal its own original weight.   Aquatic organisms have many adaptations to help their buoyancy so that they do not sink to the ocean floor.

39. IN OTHER WORDS…  Determined by how well an object floats, or sinks, in water  The more water pushing against it, the more buoyant the object

40. LIGHT & SOUND   Light and sound behave very differently in water than in air.   Most light wavelengths are quickly absorbed by water.   This explains why the sea is blue   And why ocean life is concentrated near its surface. Almost the entire marine food chain relies on light energy driving plant growth. Sound, in contrast, travels better in water, a fact exploited by animals such as dolphins

41. Light

42. LIGHT IN THE OCEAN   White light, such as sunlight, contains a mixture of light wavelengths, ranging from long (red) to short (violet).   Ocean water strongly absorbs red, orange, and yellow light, so only some blue and a little green and violet light reach beyond a depth of about 130 ft (40m).   At 300 ft (90m), most of even the blue light (the most penetrating) has been absorbed, while below 650 ft (200 m), the only light comes from bioluminescent organisms, which produce their own light.

43.   Water not only changes the color of sunlight, it dramatically changes its intensity.   In clear ocean water, visible light decreases approximately 10-fold for every 75 m (250 ft) that you descend.   This means that at: 75 m (250 ft) the light is 10% as bright as it was at the surface; and at just twice that depth, 150 m (500 ft), it is another 10-fold dimmer, or 1% of surface light. Below this depth there is insufficient light for photosynthesis, but there is still plenty of light for seeing. This is because eyes are useful over an astonishing range of intensities.

44. Describe changes in the intensity of light.  Ocean water absorbs red, orange, and yellow light strongly  Only some blue and a little green and violet light reach past 130 feet.  At 300 feet, most of all the light has been absorbed red wavelengths absorbed more readily by water than blue wavelengths red wavelengths absorbed more readily by water than blue wavelengths blue light penetrates deepest in the oceans blue light penetrates deepest in the oceans

45. Why is the sea blue?  The sea surface reflects the blue sky  The main reason is that most of the light is absorbed by the ocean, except for sonic blue and green light, which are the colors reflected back by particles in the ocean or the sea bed.

46. Sea Colors  . Occasionally, living organisms, such as “blooms” of plankton, can turn patches of the sea vivid colors.   Ocean Shades- A green sea is sometimes caused by the presence of algae. Turquoise is the usual shade in clear tropical waters, while gray water flecked with white foam is typical of windy, rainy, overcast days.

47. In what ways do sea colors change?  Windy – flecked with white trapped bubbles of air  Rain – darker, gray-green seas because rain interferes with light transmission  Algae – can cause green seas

48. Describe White Light  White light contains a mixture of wavelengths of different color light

49. Describe light color penetration in the ocean.  Light Intensity decreases with depth 0-100 m (photic zone) 0-100 m (photic zone) 100-1000m 100-1000m >1000 >1000

50. What is bioluminescence?  The “cold light” emitted by a bioluminescent organism is produced by energy released from chemical reactions occurring inside (or ejected by) the organism. Cold light means less than 20% of the light generates thermal radiation, or heat. Cold light means less than 20% of the light generates thermal radiation, or heat. Creatures produce the chemicals luciferin (a pigment) and luciferase (an enzyme). Creatures produce the chemicals luciferin (a pigment) and luciferase (an enzyme). The luciferin reacts with oxygen to create light. The luciferin reacts with oxygen to create light.  On land, only a few animals (fireflies) do this, but in the ocean, thousands do.  Used for: Defense, Finding or luring prey, Communication and Signaling to potential mates

51. BIOLUMINESCENCE

54. Examples of Bioluminescence  Antarctic Krill: found in the Antarctic waters of the Southern Ocean

55. Sea pens  Found in tropical and temperate waters worldwide

56. Jellyfish  Aequorea victoria is a jellyfish in Puget Sound, Washington State, from which the luminescent protein aequorin and the fluorescent molecule GFP (green fluorescent protein) have been extracted, purified, and eventually cloned in the 1990’s GFP (green fluorescent protein)GFP (green fluorescent protein)  Green flourescent protein (GFP) has been injected to detect many types of cancer cells

57.  Rainbow Glow jellyfish New species discovered in 2009 in Australia New species discovered in 2009 in Australia

58. Mollusks  Firefly squid – bioluminescent smokescreen and pinprick lights to confuse predators

59.  Spanish Shawl sea slug: native to the west coast of North America and further south native to the west coast of North America and further south

60. Fish  Hatchetfish – reflect downwelling light to camouflage their silhouette  Dragonfish – produces a beam of red light beneath its eye to spotlight its prey

61.  Lantern fish -  Anglerfish -

62.  Cowfish

63. UNDERWATER SOUND   Water is an excellent sound conductor.   This means that water does not absorb sound, so it can travel for great distances before it dies out.   The speed of sound in the water is 4,750 to 5,150 ft per second. This time increases by 7 ft per second whenever the temperature increases by 1degree F.   The oceans are noisier than might be imagined.

64. The sources of sound underwater   Sources of sound include: Ships and submarines Earthquakes and underwater landslides The sounds of icebergs braking off glaciers and ice shelves Sounds from ocean animals, such as whales and dolphins and other sea creatures… They make noise while swimming, when they are frightened, to find food, to send out warnings, to check out their surroundings, and to talk to each other

66. Echolocation   Dolphins and some whales us a process called echolocation.   First, they send out a series of clicks and whistles and then listen for echoes as the sounds bounce off objects (other fish, boats, reefs, etc.) in their path.   From the direction and strength of the echo, these animals can develop a mental image of their environment.   They can “see” the size of objects in their path and how far away the objects are.

67. SONAR   The sonar we use to study the ocean floor works like echolocation.   By sending out signals and retrieving the echoes, we can develop pictures of all the features on the ocean floor.   We can also find objects on the bottom, like shipwrecks or mines, and in the water column, like submarines or large schools of fish.   Sound waves travel faster and farther underwater than they do in air.   Their speed underwater is about 5,000 ft (1,500 m) per second and is increased by a rise in the pressure (depth) of the water and decreased by a drop in temperature.

69. How does sound travel change with depth?   Speed of sound travel in water increases with pressure and decreases with temperature drop Therefore, the deeper you go, the faster and farther sound moves until you get to a certain temperature

70. What is the SOFAR Channel?   Scientists found one part of the ocean that conducts sound a bit differently from the rest. Sound Fixing and Ranging channel   The depth at which the speed of sound is minimum; Thus, loud noises can be heard for thousands of km Sound generated by Navy test in Indian Ocean at SOFAR layer was heard as far away as the Oregon coast.   May affect behavior and anatomy of marine organisms It is believed to be the channel that whales use for communication over great distances   SOFAR- minimum velocity layer; sound travels slowly, sound is more efficient; found at thermocline layer

71.   Therefore, a sound wave traveling through a thermocline (a region of rapid change in temperature with depth) tends to bend downward as the speed of sound decreases with decreasing water temperature,   but then is refracted back upward as the speed of sound increases with increasing depth and pressure. This up-down-up-down bending of low- frequency sound waves allows the sound to travel many thousands of meters without the signal losing significant energy.

72.  The velocity of sound slows as the water temperature decreases approaching the thermocline.  Beneath the thermocline the temperature is constant, but increasing pressure causes the speed of sound to increase

73. SOFAR- minimum velocity layer; sound travels slowly, sound is more efficient; found at thermocline layer Since sound speed varies with temperature, pressure and salinity there are considerable variations in sound velocity both spatially (with depth / geographically) and temporally (daily / seasonally). Closest to the surface (zone 1) there is an isothermal layer created and maintained by mixing due to wind and waves. Within this layer which can be up to 200m deep the sound velocity increases slowly with depth due to the increasing pressure. The middle layer (zone 2) is the thermocline. Here the sound velocity decreases rapidly with depth due to the decreasing temperature. The base of the permanent thermocline varies greatly with latitude but is typically found at a depth of about a 1000m. Within the deepest region (zone 3) below the permanent thermocline the temperature change is less dramatic. Here the sound velocity shows a further increase with depth due to increasing pressure (like the surface layer). These areas effectively trap and focus sound waves and are called 'sound channels'. These are the deep and shallow sound channels. Sound travels very efficiently in sound channels and for this reason they are often utilized for underwater communications. The deep sound channel is often called the Sound Fixing And Ranging (SOFAR) channel. The depth of the SOFAR channel varies considerably geographically. Typically it is found at around 1500m depth at mid-latitudes, has a depth of about 500m between 50 to 60 degrees north (near Britain), and reaches the surface in Polar latitudes. The average depth of the deep sound channel is approximately 1000m. The depth of the SOFAR channel is also effected by topographic features, which may promote mixing between deeper and shallower water masses thus modifying both the temperature and sound velocity profiles.

74. Depth (m) 0 500 1000 1500 2000 SOFAR Channel Distance SOFAR channel sound rays

75. What contribution did Walter Munk make?   Austrian-American scientist, born 1917   pioneered the use of sound waves in oceanography A professor at the Scripps Institute of Oceanography in San Diego, California,  Demonstrated that by studying the patterns and speed of sound propagation underwater, you could chart the ocean floor features &  Demonstrated that by studying the patterns and speed of sound propagation underwater, you could chart the ocean floor features & information can be obtained about the large-scale structure of ocean basins.

76. Describe the relationship between sound and pressure.  As temperature decreases, the speed of sound decreases  as pressure (depth) increases, the speed of sound increases.