January 30th lecture Flashcards
What is heat capacity?
The amount of heat needed to heat 1g o fa substance by 1C
What is Sensible heat?
Heat that raises or lowers the temperature of an object but does not change its phase
What is latent heat?
Heat added or removed that does not change the temperature of a substance but leads to a change in phase.
What is ocean waters light absorbing properties?
Water absorbed Electromagnetic radiation, with the depth of penetration depending on the wavelength.
How deep can most EM radation penetrate in the ocean?
only a few cm’s or m’s at most.
How far can light penetrate the ocean’s water?
Light can go farther than most Electromagnetic radiation, although the distance is still dependent on wavelength.
on average light goes down 100m, where about 1% if its energy remains
What is the Photic Zone?
The area of the ocean where photosynthesis occurs, within the top 100m of the ocean.
Why is light penetrance reduced near the coast and in estuarine waters?
Due to the large amounts of suspended sediments in the water
What wavelength of light goes deepest in ocean water?
blue light range goes the deepest in the ocean water
How does the low penetration of light influence how we study the ocean?
The low penetration of light into the ocean is why we radar and lasers cannot be used to study the oceans interior. as they get absorbed quickly
How does light scatter or reflect?
Light is scattered when photons bounce off water molecules and/or suspended sediments
In general what direction does scattering happen in the ocean?
all directions
What wavelength of light has the greatest chance of being scattered?
Blue light as it penetrates the deepest (smallest wavelength)
Why is running water seen as green or brown?
it is due to the mixing of scatterd light within the water.
How can we determine ocean color?
It is determined by the location of phytoplankton, sediments, etc.
as particles reflect light, and we see the color that they reflect.
How is sound transmitted in the ocean?
Sound is transmitted by the vibration of adjacent molecules ( and thus can’t travel in a vacuum )
How are sound waves produced?
Sound waves are produced through pressure changes between molecules
Is sound also affect as much as light is by the ocean?
No, that is why we can use Sonar to study the ocean. and why whales communicate using sound waves.
How fast is the speed of sound in water compaired to air?
Sound waves travel 4x faster underwater than in air
What increases the speed of sound underwater?
The speed of sound increases as salinity, temperature, and pressure increase.
Are sound waves that travel vertically affected by changes in density among ocean layers?
No very much no
Are sound waves that travel at different angels other than vertically affected by density differences in water?
Yes , greatly effected. They are deflected as they hit sloping density layers
What is a shadow zone?
A region where sound pulses can’t reach
What is a sound channel?
A region associated with the sound speed minimum where sound waves that enter are trapped. This allows them to travel great distances with little loss of energy.
What is acoustic thermography?
This is a technique to accurately determine travel times in water over large distances by noting how the speed of sound changes with temperature
How is thermography being used today?
It is used to help detect the effects of climate change
How does Thermography work?
You send a low frequency sound in a sound channel around the world, and measure the time taken to get to certin points at different locations around the globe.
because heat causes sound to travel faster, if the ocean is warming then the sound waves will complete the trip faster than before when it was at a lower temperature.
