Chap 6 notes
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Heat and temperature are not the same - temperature is an object's response to heat input or removal. Water moderates global temperatures through its thermal properties - it stores heat during the day and releases it at night. The structure and movement of oceans depends on water density, which varies with temperature and salinity. A water molecule is made of two hydrogen atoms and one oxygen atom bonded together. Hydrogen bonds between water molecules give water many unique properties, such as high surface tension and the ability to absorb large amounts of heat with little temperature change. Ocean stratification into layers depends on variation in temperature and salinity with depth.
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Chap 6 notes
- 1. Heat and Temperature are not the same thing, Temperature is an objects response to an input (or removal) of heat. - Not all substances respond in the same way The influence of water on global temperatures. Liquid waters thermal characteristics prevent broad swings of temperature during day and right, and through a longer span, during winter and summer. Heat is stored in the ocean during the day and released at night. The other big idea is the influence of density on ocean structure. The oceans structure and large scale movement depends on changes in the density of seawater, with density dependent on temperature and salt content. Pure water is a compound- a substance that contains two or more different elements in a fixed proportion. An element is a substance composed of identical particles, called atoms that cant be broken into simpler substances by chemical means. Water is a molecule- a group of atoms held together by chemical bonds Chemical bonds are the energy relationships between atoms that hold them together and are formed when electrons (negatively charges particles are found toward the inside of an atom) The bonds formed by shared pairs of electrons are known as covalent bonds Protons are the positively charged particles Polar molecule- When the water molecule behaves something like a magnet: ITS POSITIVE end attracts particles that have a NEGATIVE END attracts particles that have Hydrogen bond- A hydrogen bond between molecules is about 5% to 10% as strong as a covalent bond within a molecule Cohesion- gives water an unusually high surface tension Surface tension is the results of a clean water glass being filled slightly above the rim Adhesion is waters tendency to stick to other materials Hydrogen bonds give water its blue color because a small amount of red light being absorbed leaving more blue light to scatter back to our eyes Why do hurricanes not originate in the sea of California? The water is too cold, sea surface, temperature is too cool. Hurricanes gradually weaken because their cutoff from their energy supply, moves over land and become cut off from their main source of energy and warm water air that rests on the top of water Can any good come out of a Hurricane? How can it benefit Humanity? Provides rain, brings moisture to the land, making new crops to be irrigated-some places would be desert islands if it werent hit with hurricanes What is water? What are some of the physical properties? Takes a lot of energy to warm up a body of water What is a water molecule? Define the term salinity? The total quantity or concentration of dissolved inorganic solids in water The volumes of dissolved solids measured in a liter
- 2. Salinity is based on a technical term called titration where a drop by drop water system goes into a glass tube, them looks at the reaction and see how many drops are there in total which measures your salinity which is done by a salinometer The oceans salinity caries from 3.3 to 3.7 by mass depending on factors such as evaporation, precipitation, and fresh water runoff from the continents but the average is 3.5%. Water can absorb large amounts of heat while changing relatively little in temperature Water becomes less dense when it freezes, hydrogen atoms in water widens from about 105 degrees to more than 109 degrees. Ice is less dense than liquid the space taken by 27 molecules in the liquid state will be occupied by only 24 water molecules in the solid lattice; but water expands about 9% as the crystal forms Annual freezing and thawing of Ice Moderates Earths temperature The heat capacity of solid ice is about half that of liquid water Ocean Surface Conditions depend on latitude temperature and Salinity The ocean is stratified by Density- cold salty water is denser than warm less salty water The ocean is stratified into 3 density Zones by Temp and Salinity The Salinity Zone, the pycnocline, and the deep zone The salinity zone or mixed layer is the upper layer of the ocean- Temp and salinity are relatively constant w/ depth in the surface zone because of the action of waves and currents, this zone consist of water in contact w/ the atmosphere and exposed to sunlight; it contains the oceans least dense water and accounted for only about 2% total ocean volume The pyccnocline is a zone in which density increases with increasing depth. It o=isolates surface water from the denser layer below, contains about 18% of all ocean water The deep zone lies below the pycnocline at depths below 1,000 meters (3,300) feet. There is little change in water density w/ increasing depth through this zone. This zone contains about 80% of all ocean water The pycnoclines rapid density increase in depth is due mainly to a decrease in water temp. The surface zone is well mixed with little decrease in temp with depth. In the next layer (the thermocline- therm stands for heat and its the middle layer) the temp rapidly drops with depth. Below the next layer, the deep zone lies only made of cold and stable water. Falling temperature is the major contributor to the formation of the pycnocline Below the thermocline water is veryyy cold and because this deep and cold layer contains the bulk of ocean water the avg. temp. Of the world ocean is chilly. Low salinity can also contribute to the pycocline in areas where precipitation is high or along coasts where freshwater runoff mixes w. surface water. Wherever precipitation exceeds evaporation, salinity will be low. The differences produce halocline- a zone of rapid salinity increase with depth. The halocline often coincides w/ the thermocline, and the combination produces a pronounced pycnocline. All these layers are water masses which is a body of water w/ characteristic temperature and salinity and therefore density. Even the deepest of these layers originates at the oceans surface Density Stratification Usually Prevents Vertical Water Movement Refraction can bend the paths of light and sound through water
- 3. Light and sound are both wave phenomena and both need refraction, the bending of waves. The transition from one medium to another must occur at an angle other than 90 degrees for the refraction to occur. The refraction of light waves by water happens similarly. The degree to which light is refracted from one medium to another is expressed as a ratio- refractive index. The higher the refractive index the greater the bending of waves between media. The refractive index of water increases with increasing salinity. Light is a form of electromagnetic radiation, or radiant energy, the travels as waves through space, air, and water. Shorter wavelengths are bluer, longer wavelengths are redder. The photic zone is the sunlit surface of Ocean; the thin film of lighted water at the top of the surface zone Scattering is what occurs as light is bounced between air or water molecules, dust particles, water droplets or other objects before being absorbed. The greater density of water makes scattering more prevalent in water than in air. Absorption of light is governed by the structure of the water molecules vibrate and the lights electromagnetic energy is converted to heat. Aphotic Zone- the Ocean underneath the photic zone lies in blackness. Sound is a form of energy transmitted by rapid pressure changes in an elastic medium. Sound intensity decreases as it travels through seawater because of spreading, scattering, and absorption. Eventually sound is absorbed and converted by molecules into a very small amount of heat. Sound travels to water much more efficiently then light. Sofar layer- sound travels slowly in the sofar layer but it moves rapidly near the bottom of the well-mixed surface layer. Temp and Salinity conditions are homogeneous there so they do not produce any refraction. This is right about the pycnocline level. Shadow zone- When an object is beyond the area of divergence it may be undetectable, very little sound energy penetrates Active Sonar- crews on board on surface ships and submarines employ this to get the projection and return through the water of pings of high frequency sound to search for objects in the ocean. Ocean sound is used to monitor climate change Chapter 7 Water can dissolve more substances than almost any other liquid, because water is a polar molecule and so when it comes into contact with compounds whose elements are held together by the attraction of opposite electrical charges (most salts), the polar water molecule will separate that compounds component elements from each other