The Hydrosphere

Text: Module 5 pages 105 - 127

Reading AssignmentsModule 5 pages 105 - 110 Module 5 pages 110 -118 Module 5 pages 118 –125 Module 5 pages 125 –127 Module 5 review pages 105 – 127

Homework AssignmentModule 5 Study Guide Questions p 129 1-11 Module 5 Study Guide Questions p 129-130 12-21

Introduction (p105)

70 of Earth covered by Water: View of Earth from space shows how much of the planet discovered by water. (see figure 5.1 page 105)

Special Nature of Earth: Special nature of Earth to a large part caused by special nature of water.

• Liquid/solid when you would think it would be a permanent gas because it is so small.

• Holds heat well large heat capacity• Changes Phase• Expand when it freezes.• All due to its electron configuration and polar nature which cause

hydrogen bonding (H of one molecule with the O of another molecule)

The Parts of the Hydrosphere and the Hydrological Cycle (p 106)

Hydrosphere (p 106): All of the water on a planet.

1. Water and the hydrological cycle

(1) States or Phases of Water. Water is the most widespread substance found in the natural environment.

Water exists in three forms: liquid, solid, and invisible vapor (gas). The forms are also called "states" or "phases". Water is very unique in many ways.

a. Water is one of the few substances that can exist in all three phases at normal earth temperatures. The term "vapor" is used for a gas that can change phase under normal earth temperatures. For example, we call oxygen (O2) a gas. But when water (H20) is a gas, we call it water vapor.

b. Water is a very small molecule, so we would guess it should be a gas all the time. But its electrical or "polar" properties and hydrogen makes the H20 molecules act like magnets to each other.

c. Water is one of the very, very few substances that expands and becomes lighter when it freezes! If it didn't expand and become lighter when it froze, the lakes and oceans could fill up with ice and the ice would sink. This would destroy much of the life in lakes and oceans.

(2) Water covers most of the earth

a. It forms the oceans, seas, lakes, and rivers that cover about 70% of the earth's surface.

b. In addition to "above ground" water, there is underground water found in the top layers of the Earth's crust and soil cover.

c. In a solid state, water exists as ice and snow and covers much of the polar and alpine regions in the form of glaciers.

d. There is also a certain amount of water contained in the air as water vapor, water droplets and ice crystals.

e. There is water in plants and animals (the biosphere).

f. Huge amounts of water are bound up in the composition of the different minerals of the Earth's crust and core.

(3) Where water is stored? (See Table 5.1 P. 107)

a. The Earth's hydrosphere contains a huge amount of water - about 1386 million cubic kilometers.

b. 97.25% of this amount is saline (salt) water; only 2.5% is freshwater (not salty). (See salt water/freshwater diagram at top of page 5)

c. Where do we find the 2.75% of freshwater?

- 68.9% of freshwater is in the form of ice and permanent snow cover in the Antarctic, the Arctic, and in the mountainous regions.

- 29.9% exists as fresh groundwater.

- 1.2% of the total amount of freshwater on Earth is concentrated in lakes, reservoirs, river systems, and swamps where it is most easily accessible for our economic needs and absolutely vital for water ecosystems.

(4) Maintaining a hydrological balance.

The total amount of water in our earth-ocean-atmospheric system remains constant. This is done by constantly cycling water from one part of the hydrosphere to another through evaporation, transportation, precipitation and runoff. This process of

moving water to different places in different phases is called the hydrological cycle. (See hydrological cycle diagram at bottom of page 5)

2. Details of the hydrological cycle

(1) Four Process: In order for the total amount of water in our earth-ocean-atmospheric system to remain constant, there must be a balance between four process: evaporation, transportation, precipitation and runoff. Keep in mind that this is a cycle, so there is no beginning or end to the cycle. We will start with evaporation, but we could start at any point in the cycle.

a. Evaporation/Transpiration: Evaporation is what happens when liquid water takes up energy and becomes a gas (actually called water vapor). Water vapor is at a higher energy state than liquid water. Water is constantly being evaporated from the oceans, lakes, rivers, puddles, wet soil (soil moisture) and even from plants and animals. Transpiration is the active evaporation casu3d by plants. Evaporation and transpiration increases the amount of water vapor in the atmosphere. A related process is called sublimation, which is when snow or ice goes directly from the solid state to the water vapor state. (An example of sublimation: ice cubes shrinking when left in your freezer for a long time.)

b. Transport: This the process of moving the water vapor by the winds from one location to another. In meteorology, this movement by the wind is called "advection". Overall, the transport of the water vapor by the wind takes the water vapor from the ocean areas to the land areas. How do we know that? Simply because we have at least some rain or snow everywhere on the earth.

c. Precipitation: Water vapor in the air goes through "condensation" or "deposition". (Condensation means water vapor changes from gas to liquid) (Deposition is when water skips the liquid stage and just goes from water vapor to directly to solid ice). After condensation or deposition, the liquid water or ice can form thick clouds, so it rains or snows. Precipitation as rain or snow brings the water molecules back to earth.

d. Infiltration and Runoff: The rain and snow hits the earth and either goes into the soil as soil moisture and ground water or goes into rivers and lakes as surface runoff. It eventually runs as groundwater flow into the groundwater (under ground aquifers) as infiltration. Also, it runsoff into rivers and streams. Then the water flows back to the oceans. This process takes longer in the winter, because the snow that falls must first melt before it can runoff. For the snow that falls on glaciers, this runoff may take many years.

See http://observe.arc.nasa.gov/nasa/earth/hydrocycle/hydro1.htmlhttp://ww2010.atmos.uiuc.edu/%28Gh%29/guides/mtr/hyd/smry.rxmlhttp://abe.www.ecn.purdue.edu/~agen521/epadir/grndwtr/hydro_cycle.html

Residence time (see Table 5.2 p 112)

Residence time: The average time a given particle will stay in a given particle.

Experiment 5.1: Evaporation, Condensation and Precipitation

Distillation – Evaporation then condensation of a mixture to separate out the individual components of a mixture.

The Ocean (p113)

Table Salt versus Chemical being a Salt:

Table salt is NaCl

Chemical Salt: A salt, in chemistry, is defined as the product formed from the neutralisation reaction of acids and bases. Salts are ionic compounds composed of cations (positively charged ions) and anions (negative ions) so that the product is electrically neutral (without a net charge). These component ions can be inorganic such as chloride (Cl−), as well as organic such as acetate (CH3COO−) and monoatomic ions such as fluoride (F−), as well as polyatomic ions such as sulfate (SO4

2−).

There are several varieties of salts. Salts that produce hydroxide ions when dissolved in water are basic salts and salts that produce hydronium ions in water acid salts. Neutral salts are those that

are neither acid nor basic salts. Zwitterions contain an anionic center and a cationic center in the same molecule but are not considered to be salts. Examples include amino acids, many metabolites, peptides and proteins.

When salts are dissolved in water, they are called electrolytes, and are able to conduct electricity, a property that is shared with molten salts. Mixtures of many different ions in solution—like in the cytoplasm of cells, in blood, urine, plant saps and mineral waters— usually do not form defined salts after evaporation of the water. Therefore, their salt content is given for the respective ions.Salinity: A measure of concentration of saltiness as the mass of a dissolved salt in a given mass of water.

See Figure 5.3 for percentages of components of Ocean Water

Ocean Coverage of Earth:

Oceans cover about 70% of the Earth's surface. As we learned in the previous page, the oceans contain roughly 97% of the Earth's water supply.

The oceans of Earth are unique in our Solar System. No other planet in our Solar System has liquid water (although recent finds on Mars indicate that Mars may have had some liquid water in the past). The oceans are home to an incredibly diverse web of life.

The oceans of Earth serve many functions, especially affecting the weather and temperature. The oceans moderate the Earth's temperature by absorbing incoming solar radiation. (The solar radiation is stored as heat energy in the water.) Then the always-moving ocean currents distribute this heat energy around the globe. This heats the land and air during winter and actually cools it during summer.

There are many types of motions in the ocean. We will talk about three of them: tides, waves and currents.

1. Ocean Tides

http://co-ops.nos.noaa.gov/restles1.htmlhttp://www.onr.navy.mil/focus/ocean/motion/tides1.htm

(1) Primary Cause: An ocean tide is the term that refers to the rise and fall of the oceans that occurs approximately twice each day. You may have heard that "The Moon's gravity is the cause of ocean tides". This is partly true. But, to be more correct, the real cause of tides is the difference in the magnitude of the force of gravity from one side of the earth to the other side of the earth.

There are many factors that influence the exact nature of a tide. Some of the factors are: • basic tidal forces of gravity,• centrifugal force,

• shape of the coast, • depth of the coastal waters.

Let's look at the diagram of the moon and the earth. We see that there are two high and two low tides each day. On the side of the earth that is closest to the moon, both the force of gravity between the earth and the centrifugal force caused by the spin of the earth work on the same direction, causing a high tide. On the opposite side of the earth, the force of gravity between the earth and moon is decreased because of the greater distance between the moon and the far surface of the earth. In addition, centrifugal force works in opposition to gravity, resulting in a net force that pulls the ocean water away from the direction of the moon and causes a high tide.

The Moon is 236,000 miles from Earth. To simplify the numbers, we can use the earth's radius ("er", of about 4000 miles) as a standard of a distance unit. So the distance from the center of the earth to the center of the moon is about 60 er. The distance from the Earth to the Moon, if we measure it from the side of the Earth nearest the Moon, is 59 er. The distance from the side of the Earth furthest from the moon to the moon is the 61 er. The force of gravity is proportional to the inverse of the square (2nd power) of the distance between the object. So, the force of gravity is much stronger on the side of the Earth closest to the moon than the side furthest away from the moon. The tidal generating force is actually proportional to the inverse of the cube (3rd power) of the distance of the object from the earth. As an equation, it is

(2) Secondary Cause- Spring and Neap tides: The Sun's gravity is a secondary cause of ocean tides. The sun is 390 times more distant from the earth than the moon. The force of the Sun's gravity is much stronger on the earth than the moon's gravity, but the difference of the force of gravity caused by the Sun from one side of the earth to the other side is much less than that of the moon. The net tidal effect is only about 46% that of the moon.

However, the Sun does have an influence on the tides. If the Sun is in line with the moon (as it is during full moon and new moon) the difference in the net gravity force from one side of the earth to the other is increased. This increased difference in the net gravity force causes very high or "spring" tides. If the sun is at right angles to the moon, the force of gravity works against the moon. So the net difference in the net gravity force from one side of the earth to the other is decreased, causing smaller or "neap" tides. Neap tides occur at the beginning of the second and fourth quarter phase of the moon.

(3) Tide Frequency. The number of tide cycles each day (tide frequency) is the result of two motions:

- the 24 hour rotation of the earth

3/1 dFt ∝

- the approximately 28 day orbit of the moon around the earth.

The combination of the two motions results in a cycle that is about 12 hours and 25 minutes long. So there are slightly less than two high and two low tides each day. It also means that the time of high and low tide shifts forward by about 50 minutes each day. For example: If a high tide is at 8:00 AM on Monday, the next high tide will be at about 8:25 PM that evening, then the next at about 8:50 AM on Tuesday.

(4) Height of Tides. The change in height of the water level due to the tides in the middle of the ocean is only a few inches. But tides near the coast can rise many feet. Tides near the coastline cause a much larger difference because the coastline acts as a block to the tide wave. The exact shape of the coastline is very critical to the height of high and low tide. If the coastline is shaped like a funnel, the difference from high to low tide can be more than 30 feet as in the case of the Bay of Fundy.

EarthMoon

Fg - Moon side

Stronger

Fg - Opposite side

Weaker

Moon is the Primary Cause of Tides

59 re

61 re

Cf

Net Force Net Force

EM

Sun is Secondary Cause of Tides

Sun

60er

23,400er

Mass = 332,000 em

Mass = 0.012 em

Spring Tides - Sun and Moon in Same Line

Neap Tides - Sun and Moon at Right Angles

2. Ocean Waves.

(1) Definition and cause: An ocean wave is the undulation (rising and falling movement) of the sea surface that is usually caused by winds. Ocean waves are "born" (generated) in an area where there is an uninterrupted distance over which the wind blows (measured in the direction of the wind) without a significant change of wind direction. This is called the fetch area. If the wind remains steady, the waves will travel across the sea until they collapse as breakers on a shore. You might call this the life cycle of a wave.

The highest part of the wave is called the "crest." The lowest part of the wave is called the "trough." Waves are also described by their height and wave length and wave period. The wave-height is the vertical distance from the crest to the trough. The wave length is the horizontal distance between the crest of one wave and the crest of the successive (next) wave.

(2) Types of Ocean Waves. There are many types of ocean waves based upon the wavelength and frequency of the waves. The waves range in size from very small ripples of a few inches to tsunamis that are dozens of feet high. Tsunamis are caused by earthquakes under the sea. Waves can be broken down into four forms: deep, intermediate, shallow, and breakers.

- Deep-water waves: an ocean wave that is traveling in water depth that is at least twice as large as the wavelength. (λ < 2 depth) These waves will not "feel" the bottom of the ocean. They will remain as swells and tend to stay at the same height with very little kinetic energy being converted to potential energy.

- Intermediate-water waves: an ocean wave that is traveling in water depth is at between 1/20 and 2 times as large as the wavelength (0.05 depth ≤ λ ≥ 2 depth). These waves will begin to "feel" the bottom of the ocean (friction) and will have some vertical growth as some kinetic energy is converted to potential energy.

- Shallow water waves: an ocean wave that is traveling in water depth less than 1/20 its wavelength. These waves will strongly "feel" the effects of friction from the bottom of the

ocean. Shallow water waves slow down, causing wavelength to decrease and height to increase as a significant amount of kinetic energy is converted into potential energy

- Breakers. When the steepness of the wave reaches 1/7 (1 unit high as compared to 7 units wide) the waves begin to break as breakers. In the open ocean, this is a factor of the wind speed and the age of the wave. As the waves come closer to shore and feel bottom, they will begin to rise in height until they reach the critical steepness of 1/7. The steepness of the bottom of the coastline will impact the type of breakers that result.

Deep Water Wave

Shallow Water Wave

7

1

Major Oceans

The Earth's oceans are all connected to one another. Until the year 2000, there were four recognized oceans: the Pacific, Atlantic, Indian, and Arctic. In the Spring of 2000, the International Hydrographic Organization defined a new ocean, the Southern Ocean (it surrounds Antarctica and extends to 60 degrees latitude).

There are also many seas (smaller branches of an ocean); seas are often partly enclosed by land. The largest seas are the South China Sea, the Caribbean Sea, and the Mediterranean Sea.

Ocean Area (square miles) Average Depth (ft) Deepest depth (ft)

Pacific Ocean 64,186,000 15,215 Mariana Trench, 36,200 ft

Atlantic Ocean 33,420,000 12,881 Puerto Rico Trench, 28,231 ft deep

Indian Ocean 28,350,000 13,002 Java Trench, 25,344 ft deepSouthern

(Antarctic) Ocean

7,848,300 14,800 Southern end of the South Sandwich Trench, 23,736

Arctic Ocean 5,106,000 3,953 Eurasia Basin, 17,881 ft deepLand 45,228,000 N/A N/A

Total 1.5075 x 108 N/A N/A

Major Ocean Currentshttp://oceancurrents.rsmas.miami.edu/

(1) Major Ocean Current Definition: The ocean waters are constantly on the move. When they move in an organized fashion for many years because of the prevailing winds and density, they are considered major ocean currents. Currents are like large rivers of water with a different density than the water surrounding them. How the major ocean currents move greatly influences climate and living conditions for both sea and land plants and animals.

(2) Deep Water Versus Surface Currents. Deep ocean currents are primarily the result of density differences in water caused by salinity (saltiness) changes and temperature. The denser water will move to displace the lighter less dense water. Surface currents are primarily driven by the winds. Because surface currents are wind driven, warmer water can be forced to replace colder dense water in the form of a warm current. The focus of this class will be understanding the major surface currents and their influences.

(3) Causes and Type of Surface Currents. The major surface currents are the result of the prevailing surface wind flow. In the equatorial region the predominant wind flow is from the east to the west, so equatorial currents tend to flow in that direction. In the midlatitudes (30 - 60 degrees), the wind is generally from the west so the ocean currents tend to move from west to east at mid latitudes. The currents in each ocean tend to follow the same pattern with four sections to the circulation system. The sections are:

a. A warm current near the equator that flows east to west.

b. A warm current along the east coast of continents that flows from south to north in the northern hemisphere and south to north in the southern hemisphere, between about 15 - 50 degrees latitude.

c. A warm current that between 50 - 60 degrees latitude from west to east.

d. A cold "upwelling" current that flows along the west coast of continents from about 50 to 15 degrees latitude. The coldness of the current is not only caused by where it came from but also because of phenomena of upwelling (upward motion of water). Upwelling occurs where the direction of the ocean flow and the Coriolis Effect caused by the spin of the earth causes deep water to move to the surface in a process called upwelling.

Below is a list of the seventeen major surface ocean currents.

Name Location TypeAgulhas Current Indian Warm Alaska Current North Pacific WarmBenguela Current South Atlantic Cool Brazil Current South Atlantic Warm

California Current North Pacific Cool Canaries Current North Atlantic Cool East Australian Current South Pacific WarmEquitorial Current Pacific Warm Gulf Stream North Atlantic Warm Humboldt (Peru) Current South Pacific Cool Kuroshio (Japan) Current North Pacific Warm Labrador Current North Atlantic Cool North Atlantic Drift North Atlantic Warm North Pacific Drift North Pacific WarmOyashio (Kamchatka) Current North Pacific Cool West Australian Current Indian Cool West Wind Drift South Pacific Cool

(4) Effects of Ocean Currents:

a. Fishing: Fish thrive in cold ocean currents because the cold currents are rich in nutrients and oxygen. Most of the commercial fish caught come from cold current regions of the world. Note: The phenomenon called "El Nino" is a disruption of the upwelling of the cold Humbolt (Peru) current.

b. Energy transport: Ocean currents transport about 10% of the energy needed to keep the worlds temperature in balance.

c. Climate and Weather: Warm currents make the climate of the Pacific Northwest , Alaska, England, and western Europe much milder than it would otherwise be. Cold currents off the west coasts of Africa, North America and South America, keep these regions much cooler than they would be otherwise. Mark Twain once said the coldest winter he ever spent was a summer in San Francisco.

Major Ocean Currents.

Warm Cold

A “generic” ocean with its currents.

Glaciers and Icebergs (p 116)

Glacier: A glacier is a large, slow moving river of ice, formed from compacted layers of snow, that slowly deforms and flows in response to gravity. Glacier ice is the largest reservoir of fresh water on Earth, and second only to oceans as the largest reservoir of total water. Glaciers cover vast areas of polar regions but are restricted to the highest mountains in the tropics. Elsewhere in the solar system, the vast polar ice caps of Mars rival those of the Earth. Geologic features created by glaciers include end, lateral, ground and medial moraines that form from glacially transported rocks and debris; U-shaped valleys and cirques at their heads, and the glacier fringe, which is the area where the glacier has recently melted into water. The word glacier comes from French via the Vulgar Latin glacia, and ultimately from Latin glacies meaning ice.

Iceberg: An iceberg is a large piece of freshwater ice that has broken off from a snow-formed glacier or ice shelf and is floating in open water[1]

Since the density of pure water ice is ca. 920 kg/m³, and that of sea water ca. 1025 kg/m³, typically, only one ninth of the volume of an iceberg is above water. The shape of the remainder under the water can be difficult to surmise from looking at what is visible above the surface. This has led to the expression "tip of the iceberg", generally applied to a problem or difficulty, meaning that the visible trouble is only a small manifestation of a larger problem.

The word iceberg is a partial loan translation from Dutch ijsberg, literally meaning mountain of ice. Frozen “salt water” solid brine surrounding fresh frozen water Icebergs are frozen freshwater

Firn: A dense pack of old snow

Glacial Ice Motion: Flows (See Figure 5.4 p 118)

• Ice shelves – Glacier part out to sea (Ross Ice shelf)• Calving – chucks of ice breaking off to form icebergs.

Experiment 5.2: Ice and Salt (p 116)

Ground Water and Soil Moisture (see Figure 5.6 p 120 )

Soil Moisture: - Soil that is not saturated with water

Groundwater: Soil that is saturated with water

Ground water is second largest source of freshwater

Roil of transpiration of deep moisture from trees

Water Table: Line between saturated (groundwater) and unsaturated soil (soil moisture)

Percolation: The process of water moving for the surface of the ground to the ground water.

Surface Water (p 122)

Made up rivers, ponds and lakes.

Salty lakes: Great Salt Lake and Dead Sea

Atmospheric Moisture (p 122)

Humidity: gas water (water vapor – not visible)

Condensation: Makes the clouds – liquid water

Adiabatic cooling: Cooling by expansion

Adiabatic warming: Cooling by evaporation

Pure adiabatic process is reversible

Cloud condensation nuclei and Precipitation process

Fog and Smog • Photochemical smog

Pseudo adiabatic process takes place when precipitation falls warming the upper atmosphere through latent heating.

Experiment 5.3 Cloud Formation (p122)

Water Pollution (p 126)

Sources:

Industrial/medical wastesPesticides, fertilizers, gasolineHuman wastesThermal Pollution – cooling macinerl/nuclear plants

Improvements – in water quality.