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Questions and Answers
What is the primary cause of spring tides?
What is the primary cause of spring tides?
What characterizes a neap tide?
What characterizes a neap tide?
Which statement about surface currents is true?
Which statement about surface currents is true?
What best defines upwelling in ocean movements?
What best defines upwelling in ocean movements?
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What is the main reason lunar tides are higher than solar tides?
What is the main reason lunar tides are higher than solar tides?
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What percentage of Earth's water is found in the oceans?
What percentage of Earth's water is found in the oceans?
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What event is hypothesized to have contributed to the initial accumulation of water on Earth?
What event is hypothesized to have contributed to the initial accumulation of water on Earth?
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Which hemisphere is almost completely covered by water?
Which hemisphere is almost completely covered by water?
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What is the primary factor that causes sea level changes over time?
What is the primary factor that causes sea level changes over time?
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What is the measure of dissolved salts in seawater called?
What is the measure of dissolved salts in seawater called?
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What term describes the highest point of a wave?
What term describes the highest point of a wave?
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What is formed when wave height increases and wave length decreases as a wave approaches the shore?
What is formed when wave height increases and wave length decreases as a wave approaches the shore?
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Which type of water body typically has the lowest salinity?
Which type of water body typically has the lowest salinity?
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Study Notes
Origin of the Oceans
- Scientists believe Earth's water came from either a distant source (like comets or meteorites) or a local source (like volcanoes), or a combination of both.
- Comets and meteorites are possible distant sources of Earth's water.
- Volcanic activity released large amounts of water vapor and other gases into the early atmosphere. This water vapor eventually condensed to form the oceans.
Distribution of Earth's Water
- The oceans hold about 97% of Earth's water.
- Fresh water makes up the remaining 3% and is found in ice caps (Greenland and Antarctica), rivers, lakes, and underground sources.
- The northern hemisphere has slightly more water than land.
- In contrast, the southern hemisphere is almost entirely covered by water.
Sea Level
- Sea level changes over time, affected by melting ice (during warm periods) or expanding glaciers (during ice ages).
- Tectonic forces also influence sea level by lifting or lowering portions of the Earth's crust.
- Scientists link rising sea levels to melting glaciers due to global warming.
Ocean and Atmosphere Interaction
- Oceans release atmospheric oxygen.
- Oceans act as a large reservoir of carbon dioxide.
- Oceans influence large-scale atmospheric moisture and heat circulation patterns.
Chemical Composition of Seawater
- Salinity measures the amount of dissolved salts in seawater.
- Seawater is denser than freshwater, and its density increases with salinity.
- Estuaries are areas with lower salinity, often where rivers meet the ocean.
Ocean Movements: Waves
- Waves are rhythmic movements that carry energy through water.
- Wind blowing over the ocean's surface creates waves.
- The highest point of a wave is the crest, and the lowest point is the trough.
- Waves become breakers when their height increases, and length decreases as they approach the shore.
Ocean Movements: Tides
- Tides are the periodic rise and fall of sea levels.
- High tide is the highest point of water rise.
- Low tide is the lowest point of water fall.
- The gravitational pull of the Sun and Moon affects the tides.
Ocean Movements: Influence of Tides
- Lunar tides are significantly stronger than solar tides due to the Moon's proximity to Earth.
- Spring tides occur when the Sun, Moon, and Earth are aligned, resulting in higher high tides and lower low tides.
- Neap tides happen when the Sun, Moon, and Earth form a right angle, causing lower high tides and higher low tides.
Ocean Movements: Currents
- Surface currents are wind-driven water movements primarily affecting the top few hundred meters of the ocean.
- These currents follow predictable patterns driven by global wind systems.
- Gyres are closed current circuits influenced by continents. Currents are deflected either north or south by land masses.
Ocean Movements: Upwelling
- Upwelling is the upward movement of ocean water.
- Upwelling occurs when surface water is moved offshore, causing deeper, colder water to rise to the surface to replace it.
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Description
Explore the fascinating origins of Earth's oceans, including the role of comets, meteorites, and volcanic activity. Understand the distribution of Earth's water, with a focus on the vast ocean coverage and fresh water sources. Discover how sea levels change over time due to climatic and tectonic influences.
