STANDARD Explain that a large portion of Earths

STANDARD Explain that a large portion of Earth’s surface is water, consisting of oceans, rivers, lakes, groundwater, and ice.

Water in Earth’s Processes

The Water Cycle Section 11 -1 • How is Earth’s water • • • distributed among saltwater and freshwater resources? How does Earth’s water move through the water cycle? Explain the steps of the water cycle. How do people and other living things use water?

Based on the Pie Chart, what does the blue or green represent on the graph?

What Does This Mean? • Earth’s Water Saltwater 97% Freshwater 3% Total Water on Earth • 2% is frozen in glaciers and ice caps • ONLY 1% IS AVAILABLE FOR HUMAN CONSUMPTION.

Water on Earth • Most of Earth’s water is saltwater (97%) • Most saltwater is found in the oceans • Only about 3% of water is freshwater • All living things must share about 1% of the total amount of water on Earth

Water on the Earth • Almost all the • water on Earth is salt water (97%). Of the three percent that is fresh water, 76% is frozen in the ice caps at the poles.

Distribution of Water on Earth • Saltwater oceans and (salt) lakes (97%) • Freshwater (3%) – Of the total Freshwater on Earth: 76% of freshwater is ice – 12% of freshwater is Shallow Groundwater – 11% of freshwater is Deep Groundwater – 0. 34% of freshwater is found in Lakes and Rivers – 0. 037% of freshwater is Water Vapor • All living things share less than 1% of total water on Earth!

The Water Cycle 1 • Water is naturally recycled through a process known as the water cycle • Water moves from bodies of water, land, and living things from Earth’s surface, up to the atmosphere and then back to Earth’s surface. • Steps for the water cycle are: evaporation, condensation, and precipitation

The Water Cycle n Thirstin's Water Cycle Animation

The Water Cycle Continuous process by which water moves through the living and nonliving parts of the environment. The source of energy that drives the water cycle is the SUN!

Evaporation • Evaporation – the process by • • which liquid water on the surface change to a gas Most evaporated water comes from oceans, and most precipitation falls back into the oceans. The salt does not get enough energy to become a gas, so it stays behind.

Cloud Formation • Clouds formation – water vapor loses energy, cools down, condenses into liquid water droplets, droplets clump together around tiny dust particles, forming clouds

The Water Cycle 3 – Water vapor also enters the air from plants. This is called transpiration. • Condensation – process by which gas molecules change into a liquid. This process forms clouds • Precipitation – process in which clouds become too heavy to hold the water droplets, and the droplets fall to the Earth’s surface as rain, sleet, snow or hail

How Do People Use Water?

How Do People Use Water? • Humans use water for household purposes, agriculture, industry, transportation, and recreation. • Agriculture/Irrigation is the process of supplying water to areas for growing crops • Industry – to make products, cool off machines • Transportation – travel upon the oceans, lakes and rivers • Recreation – exercise and sports

Water and Living Things • Water is important for living things to grow, reproduce and carry on other essential processes. • Photosynthesis – plants use water, carbon dioxide and sunlight to make their own food • Habitat – place an organism lives and provides the things it needs to survive

Water Cycle Vocabulary • Evaporation: the process of energy changing liquid water into water vapor (a gas) and rising in the air • Condensation: the cooling of water vapor, which changes it back into a liquid • Precipitation: the release of condensed water that the air cannot hold any longer. Precipitation occurs in the form of rain, hail, sleet, or snow

• Transpiration: : the process by which plants lose water out of their leaves and into the air • Collection- When water collects together to form a body of water. Lakes, puddles, oceans, etc.

Water Cycle Vocabulary • Clouds: condensed water made up of water droplets and tiny dust particles • Groundwater: water that collects above the bedrock layer and moves like an underground river

• Percolation/infiltration: the downward movement of absorbed precipitation by the soil, which eventually collects as groundwater • Runoff: water that flows over the surface of land

Answers to The Water Cycle 1. A = precipitation B = condensation C = evaporation 2. The sun 3. Transpiration is the process in which the leaves of plants give off water 4. Water vapor cools, cold air causes water to condense, water droplets clump together around tiny dust particles, causing clouds to form 5. The oceans are where most precipitation falls and where most evaporation takes place 6. Groundwater 7. irrigation

Quick Check More than 97% of Earth’s total water supply is found in A. B. C. D. ice sheets. groundwater. the atmosphere. the oceans.

Quick Check The energy the drives the water cycle comes from A. the sun. B. the Earth. C. the rain. D. oceans.

Quick Check Rain that falls on a steep, paved street during a thunderstorm would most likely be called: A. groundwater. B. runoff. C. a spring. D. a reservoir.

Quick Check More than two-thirds of Earth’s freshwater is found in A. B. C. D. rivers and streams. ponds and lakes. glaciers and icebergs. wetlands.

Quick Check How does the water cycle renew Earth’s supply of fresh water? A. B. C. D. evaporation. condensation the sun precipitation

Quick Check Clouds are an example of which stage of the water cycle? A. Condensation B. evaporation C. percolation D. precipitation

Ocean Water Chemistry • How salty is ocean water? • • • (5) How do the conditions in the ocean change with depth? (5) How did the ocean form, and how is it currently divided? (4) Describe one factor that increases the salinity of seawater and one factor that decreases salinity. (4)

The Salty Ocean (1) • Salinity- the measure of the amount of dissolved salts in a given amount of water • The average amount of salt in ocean water is about 3. 5% or 35 grams of salt per one kilogram (1000 g) of water • Ocean water carries many different dissolved salts • Sodium Chloride (table salt) is the most abundant salt in the ocean

The Salty Ocean (2) • The main substance dissolved in ocean water is sodium chloride (Na. Cl) or table salt. • Other dissolved solid substances are sulfate, magnesium, calcium, and potassium. • Solid substances dissolved in sea water come from rivers, streams, rocks from the shore, volcanoes and underwater hot springs. • The concentration of all the dissolved substances in sea water is about 3. 5%.

Gases Found in the Oceans • The oceans also hold dissolved gases, such as oxygen and carbon dioxide. • Marine life such as fish need dissolved oxygen in sea water to live. • Most oxygen in oceans come from the atmosphere because it is closer to the surface of the water. • Sea plants such as seaweeds need carbon dioxide to survive. They get it from the dissolved carbon dioxide in sea water.

The Salty Ocean • Temperature decreases in the ocean with depth • Pressure increases with depth in the ocean • Scuba divers are prevented from descending farther than 40 m because of pressure • Further depth will cause the lungs to collapse!

How Did the Oceans Form? • About 4 billion years ago, the Earth cooled enough for water vapor to condense. • The water began to fall as rain. • The rain filled the deeper levels of Earth’s surface and the first oceans began to form.

Divisions of the Global Oceans • Pacific- the largest ocean; getting smaller • Atlantic- the second largest; getting larger • Indian- third largest; • Southern- located along the border of Antarctica • Arctic- smallest ocean; most oceanographers consider it as an extension of the Pacific and Atlantic Oceans

Location of the World’s Oceans • The Pacific Ocean is the largest ocean. It is bordered by North America, South America, Asia, Australia, and Antarctica • The Atlantic is the second largest ocean. It is bordered by N. America, S. America, Africa, Europe, and Antarctica. • The third largest ocean is the Indian Ocean. It lies between the countries of India, Pakistan, Australia, and the continents of Africa and Antarctica.

Arctic Ocean North Atlantic Ocean Pacific Ocean South Atlantic Ocean Indian Ocean Southern Ocean

Increasing and Decreasing Salinity • Salinity- the measure of the amount of dissolved salts in a given amount of water. • Factors increasing salinity include : evaporation freezing • factors decreasing salinity include precipitation rivers dumping water into oceans

Characteristics of Ocean Water • Ocean water is salty • Chock-full of solids • Climate affects salinity • Water movement affects salinity • Temperate zones • Surface temperature Changes

Ocean Water is Salty • Most of the salt found in oceans is sodium chloride (table salt). • Salts have been added to the oceans for billions • of years by running waters (rivers, streams) which dissolve various minerals, and then dump the water into the oceans. Also, solid materials come from volcanic eruptions, hot springs, ocean waves crashing against rocks

Chock-Full of Solids • Salinity- the measure of the amount of dissolved salts in a given amount of water. • Measured in grams (g). • 1 kg (1000 g) of ocean water carries an average of 35 g of salt (3. 5%). • During the water cycle, fresh water from the ocean is evaporated leaving only the salts behind.

Climate Affects Salinity • Some parts of the ocean are saltier than other parts of the ocean. • Coastal waters in places with hotter, drier climates have a higher salinity. • Coastal waters in places with cooler, more humid climates have a lower salinity. • Main reason: evaporation • Coastal waters in general have less salinity because more fresh water from rivers run into the oceans in these areas.

Water Movement Affects Salinity • Some parts of the ocean (bays, seas, gulfs) move less than other parts. • Also, some parts of the open ocean that do not have currents run through them can be slow moving. • Slower-moving areas of water develop high salinity.

Temperate Zones • Temperature of ocean water decreases with depth. • Water in the ocean is divided into three layers by temperate. • Top layer (surface zone) • Middle layer (thermocline zone) • Bottom layer (deep zone)

Temperature Changes • Temperature in the surface zones vary with latitude and the time of the year. • Parts of the ocean along the equator are warm because it receives more direct sunlight per year than areas closer to the poles.

Answers to Ocean Water Chemistry 1. 2. 3. 4. 5. 6. 7. 8. Surface to about 200 m 17. 5°C Transition zone Bottom of surface zone to 1 km Deep zone 3. 5°C 35 g of salt per 1 kg of water Precipitation, rivers, evaporation, freezing 9. Ocean water because it contains salt 10. Sodium chloride 11. Because this is where oceans meet the atmosphere and where algae live 12. The pressure of the water 13. Submersible 14. Salinity 15. Water column

Quick Check Ocean water is more dense than freshwater at the same temperature because of A. B. C. D. pressure. salinity. the Coriolis effect. upwelling.

Quick Check The most common substances dissolved in ocean water are A. B. C. D. sodium and chloride. potassium and sodium. calcium and chloride.

Quick Check The concentration of all dissolved substances in seawater is 3. 5%. How many grams of dissolved substances are in 200 grams of saltwater? A. 3. 5 B. 7. 0 C. 57 D. 200

Quick Check Which shows the correct order of Earth’s three major oceans from largest to smallest? A. Pacific, Atlantic. Indian B. Atlantic, Pacific, Indian C. Indian, Atlantic, Pacific D. Atlantic, Indian, Pacific

Quick Check Which continents border the Atlantic Ocean? A. North America, Asia, Australia B. Asia, Australia, Africa C. North America, South America, Europe, Africa D. South America, Europe, Asia, Africa

Quick Check Salinity is the average amount of ____ Dissolved in water. A. sugar B. oxygen C. carbon dioxide D. salt

Quick Check What is the salinity of saltwater? As you descend deeper into the ocean temperature _______ and pressure _____. The two sources of oxygen in ocean water are _____ and _____.

Exploring the Ocean EQ: What are some features of the ocean floor?

Exploring the Ocean • What factors make ocean floor research difficult ? (2) • What is SONAR? (5) • What are some features of the ocean floor ? (7)

What factors make ocean floor research difficult? • Scientists had to develop new technology to study the deep ocean floor because of three factors: 1. cold temperature 2. increased pressure 3. darkness As you descend deeper into the ocean, these (3) factors increase

SONAR • Oceanographers have mapped the ocean floors by using special equipment. • SONAR stands for sound navigation and ranging. It is a system that uses sound waves to calculate the distance to an object. • Oceanographers study the oceans by: -sonar -satellite • Echo sounding, (pings), measure the time it takes a pulse of sound to go from the ship to the ocean floor and echo back to the ship. • The speed of sound in sea water averages about 1520 m per second.

What are some of the features of the ocean floor? • The seven features of the ocean floor are: – Continental shelf: a gentle sloping, shallow area of the ocean floor that extends outward from the edge of the continent. – Continental slope: marks the true edge of a continent, a steady slope where rock that makes up the continent stops and the rock that makes up the ocean floor begin. – Abyssal plain: smooth, flat region of the ocean floor

What are some of the features of the ocean floor? – Mid-ocean ridge: a continuous range of mountains that wind around Earth’s ocean floor. – Seamounts: mountains completely under water; extinct volcanoes – Deep-sea Trench: canyons on the ocean floor that are the deepest spots on Earth. – Volcanic Island: very tall mountains created by the cooling and hardening of erupting volcanoes on the ocean floor. – Guyot: a flat-top seamount flattened by the action of waves

Subsurface Topography

Answers to Exploring the Ocean 1. Darkness, cold, and extreme pressure 2. Sound navigation and ranging, is a system that uses sound 3. 4. 5. 6. 7. 8. 9. waves to calculate the distance to an object Mid-ocean ridge – a continuous range of mountains that winds around Earth Trench – a steep sided canyon in the deep ocean floor Continental slope – an incline at the edge of a continental shelf Abyssal plain – the smooth, nearly flat region of the ocean floor Seamount – a mountain that is completely under water Continental shelf – a gently sloping, shallow area of the ocean floor that extends outward from the edge of a continent Volcanic island – the peak of a volcano that beaks the ocean surface

Quick Check A smooth, nearly flat region of the ocean floor is call a(n) A. trench. B. mid-ocean ridge. C. abyssal plain. D. sea mount.

Quick Check Which ocean floor feature makes up the deepest parts of the ocean? A. abyssal plain B. mid-ocean ridge. C. deep-sea trench. D. sea mount

Quick Check What three (3) factors make ocean floor research difficult? 1. _______ 2. ______ 3. ______

Quick Check What are some features of the ocean floor? 1. _____ 2. _____ 3. _____ 4. _____ 5. _____ 6. _____

Lesson 12 Waves, Currents, and Tides EQ: What causes the ocean to move?

Waves • A wave is a disturbance that transfers energy through matter or space. • Wind transfers energy into the sea causing waves to occur. • Undersea earthquakes and landslides can also put energy into the water to produce ocean waves.

Waves • The size of a wave depends on the amount of energy that is transferred to the water. • The amount of energy transferred depends on three things: – – – Wind speed Length of time it blows Distance over which it blows • As each of these factors increase, so does the size of the wave.

Ocean Currents • Winds are responsible for ocean currents. • A surface current is an ocean current that moves along the top part of an ocean. • Surface currents are moved by prevailing winds. • Prevailing winds are winds that blow in regular directions almost all the time.

Ocean Currents • Surface currents can be cold or warm. • Those that flow from the poles toward the equator are cold. • Those that flow from the equator towards the poles are warm. • The Gulf Stream is a warm current that flows northward up the east coast of the United States toward Great Britain and western Europe.

Tides • A tide is the rise and fall of the ocean’s surface caused mostly by the gravitational pull of the moon. • At high tide, the ocean water has risen as high as it will go on a shore. • At low tide, the ocean water has fallen as low as it can go on a shore.

Tides • Earth’s rotation on its axis affects which tides will occur at a certain place on Earth. • High tides occur about every 12 hrs. • Low tides occur about every 12 hours. • The time between low tide and high tide is about 6 hrs.

Quick Check What causes tides but NOT waves and currents? A. winds and the moon’s gravity B. mostly the moon’s gravity C. mostly the sun’s gravity D. only winds

Quick Check What is the main cause of the Gulf Stream? A. storms B. winds that blow now and then C. winds that blow in regular directions D. the moon’s gravity

Quick Check If the first high tide of the day occurs at 1: 00 a. m. , the next high tide will come closest to A. 7: 00 a. m. B. 7: 00 p. m. C. 1: 00 a. m. the next day D. 1: 00 p. m.

Quick Check What is the cause waves and currents but NOT tides? A. wind B. the moon’s gravity C. the sun’s gravity D. Earth’s gravity

Quick Check What is the cause of most ocean waves? A. The climate B. The large ships in the ocean C. The moon D. The wind

Quick Check A wave will increase in height when the distance over which the wind blows over the sea A. increases. B. decreases. C. stays the same. D is 0 kilometers.

Quick Check The wave will increase in height when the speed of the wind A. remains unchanged for a long time. B. decreases. C. increases. D. changes direction.

Quick Check Which will produce the highest wave? A. wind speed of 10 km/h B. wind speed of 20 km/h C. wind speed of 30 km/h D. wind speed of 40 km/h

Quick Check Which unit of measurement would you use to express the area of the Atlantic Ocean? A. m B. km C. m² D. km²

Section 13 – 1 Wave Action

Wave Action How does a wave form? How does wavelength and wave height change as a wave enters shallow water? What factors determine the size of a wave?

EQ: What Causes a Waves to Form? • A wave is a disturbance that transfers energy through matter or space. • Most waves form when winds blowing across the water’s surface transmit their energy to the water. • Wind transfers energy into the sea causing waves to occur. • Undersea earthquakes and landslides can also put energy into the water to produce ocean waves.

Parts of a Wave

Describing Waves • Crest – highest part of a wave • Trough – lowest part of a wave • Wavelength – horizontal distance between crests or troughs • Wave height – vertical distance from the crest to the trough • Frequency – number of waves that pass a point in a certain amount of time

Diagram of a Wave

How does the water move in a wave? Like the bottle in the picture, water remains in the same place as wave travel through it.

Size of a Wave • The size of a wave depends on the amount of energy that is transferred to the water. • The amount of energy transferred depends on three things: – Wind speed – Length of time it blows – Distance over which it blows • As each of these factors increase, so does the size of the wave.

How Waves Change Near Shore • In deep waters, waves travel as long, low waves called swells. • Near shore, the wave height increases and the wavelength decreases. • When the wave reaches a certain height, the crest of the wave topples. The wave breaks onto the shore, forming surf.

How Waves Affect the Shore • Longshore Drift – movement of sand along the beach at an angle • Rip Currents – a rush of water that flows rapidly back to sea through a narrow opening • Sandbar –as waves slow down, they deposit the sand they are carrying on the shallow, underwater slope in a long ridge

Longshore Drift

Rip Currents Sandbars

Reducing Beach Erosion • Over time, erosion can wear away a beach • Threatens homes, buildings, property • groin – a wall of rocks or concrete to reduce erosion along a stretch of beach • Building groins can increase the amount of erosion further down the beach

Answers to Wave Action 1. 2. 3. 4. 5. 6. 7. Crest Wavelength Trough Wave height The waves height increases and its wavelength decreases When the waves come into the shore at an angle, resulting in a movement of sand along the beach Build a groin 8. Wave – the movement of energy through water (b) 9. Frequency – the number of waves that pass a point in a given amount of time (d) 10. Longshore drift – the movement of sand down a beach (a) 11. Sandbar – a long, low ridge of sand deposited offshore as waves go back out to sea (c) 12. Rip current – a rush of water that flows out from the shore through a narrow opening (f) 13. Groin – a wall of rocks or concrete built outward from a beach to prevent erosion (e)

Quick Check What is the cause of most ocean waves? A. The climate B. The large ships in the ocean C. The moon D. The wind

Quick Check A wave will increase in height when the distance over which the wind blows over the sea A. increases. B. decreases. C. stays the same. D is 0 kilometers.

Quick Check The wave will increase in height when the speed of the wind A. remains unchanged for a long time. B. decreases. C. increases. D. changes direction.

Quick Check Which will produce the highest wave? A. wind speed of 10 km/h B. wind speed of 20 km/h C. wind speed of 30 km/h D. wind speed of 40 km/h

Quick Check Rolling waves with a large distance between crests have a long A. wave height B. wavelength C. frequency D. trough

Quick Check Groins are built to reduce the effect of A. tsunamis. B. longshore drift. C. rip currents. D. deep currents.

Quick Check Sand is gradually carried down the beach by A. groins B. sandbars C. crests D. longshore drift

Section 13 - 4 Currents and Climate EQ: What forces cause surface currents and deep currents?

What Causes Surface Currents to Move? What force causes surface currents? How do surface currents affect climate on land? What force cause deep currents? What is El Niño?

What is the difference between a wave and a current? Studyjams Watch the Study Jams video!

Surface Currents • Surface currents are driven mainly by winds and follow global wind patterns, moving in circular patterns in ocean basins. • Surface currents affect water to a depth of several hundred meters. • Coriolis effect- the effect of Earth’s rotation on the direction of winds and currents

The Coriolis Effect

Surface Currents • Winds are responsible for ocean surface currents. • A surface current is an ocean current that moves along the top part of an ocean. • Surface currents are moved by prevailing winds. • Prevailing winds are winds that blow in regular directions almost all the time.

How Surface Currents Affect Climate • A surface current warms or cools the air above it, influencing the climate of the land near the coast. • Currents are large streams of moving water that flow through the oceans • Currents affect climate by moving cold and warm water around the globe. • Climate is the pattern of temperature and precipitation typical of an area over a long period of time.

Deep Currents • Deep currents are caused by differences in density rather than surface winds. • Cold waters at the bottom of the ocean creep slowly across the ocean floor. • Deep currents move and mix water around the world. • They move much slower than surface currents.

Upwelling • Upwelling is the upward movement of cold water from the ocean depths. • As wind blows away the warm surface water, cold water rises to replace it. • Upwelling brings up tiny ocean organisms, minerals, and other nutrients from the deeper layers of the water.

El Niño • El Niño- an abnormal climate event that occurs every 2 to 7 years in the Pacific Ocean. • This causes a sheet of warm water to move eastward toward the South American coast. • El Niño can last for one to two years before the usual winds and currents return. This damage in Southern California was the result of excessive rain caused by El Niño in 1997

Answers to Currents and Climate 1. Surface 2. Warm or cold 3. Differences in density 4. Cold 5. By moving warm or cold water around the globe, warming or cooling the air above 6. Upwelling increases the supply of nutrients by bringing up tiny ocean organisms, minerals and other materials from the deeper layers of the water 7. Currents 8. Coriolis effect 9. Climate 10. El Niño

Quick Check Surface Currents are caused by A. gravitational pull of the moon. B. gravitational pull of the sun. C. Winds, the earth’s rotation, and differences in water density. D. the earth’s rotation.

Quick Check Winds and currents move in curved paths because of A. B. C. D. the Coriolis effect. longshore drift. wave height. tides.

Quick Check What is the MAIN cause of the Gulf Stream? A. storms B. winds that blow now and then C. winds that blow in regular directions D. the moon’s gravity

Section 13 - 2 Tides EQ: What causes tides?

Tides What causes tides? How can tides be used to generate electricity? Describe the positions of the sun and the moon, in relation to Earth when spring tides occur.

What causes tides? • Tides are caused by the • • interaction of Earth, the moon, and the sun. The moon pulls on the water on the side closest to it more strongly than it pulls on the center of the Earth. This pull creates a bulge of water, called a tidal bulge, on the side of Earth facing the moon. The water opposite the moon is pulled toward the moon less strongly than the water facing the moon. This water is “left behind, ” forming a second bulge.

The Daily Tide Cycle • As Earth turns completely around once each day, • people on or near the shore observe the rise and fall of the tides as they reach the area of each tidal bulge. The high tides occur about 12 hrs. and 25 mins. Apart in each location.

Tides occur at different locations on Earth because the Earth rotates more quickly than the moon revolves around the Earth.

Effects of Daily Tides

The Monthly Tide Cycle • Changes in the positions of Earth, the moon, and the sun • • • affect the height of the tides during a month. Twice a month, at the new moon and the full moon, the sun and moon are in a straight line. Their combined gravitational pull produces the greatest range between high and low tide, called a spring tide. In between spring tides, at the first and third quarters of the month, the sun and moon pull at right angles to each other, producing a neap tide. A neap tide is a tide with the least difference between low and high tide. The movement of large amounts of water between high and low tide are a source of potential energy—energy that is stored and waiting to be used.

Spring Tides and Neap Tides

Answers to Tides 1. A and D 2. C or E 3. Spring 4. Lower 5. Spring 6. Greater 7. Neap tide – tide with the least difference between high and low tide (c) 8. High tide – tide in which water reaches its highest point on the beach day (d) 9. Spring tide – tide with the greatest difference between high and low tide (a) 10. Low tide – tide in which water reaches its lowest point on the beach day (b)

Quick Check What causes tides but NOT waves and currents? A. winds and the moon’s gravity B. mostly the moon’s gravity C. mostly the sun’s gravity D. only winds

Quick Check At the full moon, the combined gravitational pulls of the sun and the moon produce a A. surface current. B. neap tide. C. spring tide. D. rip current.

Quick Check A tide which water reaches its lowest point on the beach day is called A. neap tide. B. high tide. C. spring tide. D. low tide.

Quick Check Tide with the least difference between high and low tide is called A. neap tide. B. high tide. C. spring tide. D. low tide.

Quick Check A tide in which water reaches its highest point on the beach day is called a A. neap tide. B. high tide. C. spring tide. D. low tide.

Quick Check If the first high tide of the day occurs at 1: 00 am, the next high tide will come closest to A. 7: 00 am B. 1: 00 am the next day C. 7: 00 pm D. 1: 00 pm

Quick Check Tide with the greatest difference between high and low tide is called a A. neap tide. B. high tide. C. spring tide. D. low tide.

Quick Check High tides occur A. once every two days. B. once a day. C. twice a day. D. four times a day.