Chapter 5: Introduction to Water

Introduction to Water and the Chapter

• Chapter 5 centers on water, also known as the hydrosphere, and builds on previous discussions of the biosphere and its components: lithosphere, atmosphere, and hydrosphere.
• Water is essential for life, serving various purposes like drinking and sustaining plant life for food.
• Water comes from sources like rivers and municipal supplies.

Water's Continuous Circulation and Forms

• Water continuously transforms circulating between oceans, the atmosphere, and land.
• Water's cycle involves the oceans, atmosphere, and land.
• Water exists as liquid in rivers, solid as ice, and gaseous as water vapor.
• Water can also be semi-liquid in clouds.
• Water transitions include water vapors turning into clouds and then liquid.

The Water Cycle Explained

• The sun heats water, causing evaporation and creating water vapor that condenses to form clouds.
• Water returns to Earth as rain, snow, or hail, eventually flowing into oceans or becoming groundwater.

Earth as a Terrarium

• Earth acts like a terrarium, with water constantly cycling through evaporation, condensation, and precipitation.
• Water continuously cycles from oceans to vapor and back to rain
• The water used today could have existed for centuries, participating in this ongoing cycle.

Sources of Fresh Water vs. Salt Water

• Fresh water sources include rivers, ponds, springs, and glaciers
• Fresh water is drinkable.
• Oceans are the major water source, containing saline water.
• River water erodes and carries sediment, depositing it in the ocean, contributing to its salinity.
• Ocean water evaporates, repeating over time, which contributes to the ocean's salinity.
• Salt is harvested through seawater evaporation.

Chapter Topics

• The chapter's topics include:
  • Distribution of water bodies
  • Analysis of oceanic circulation
  • Nature of waves, tides, and ocean currents
  • Occurrence of events like tsunamis
  • Additional relevant information and NCERT solutions

Distribution of Water Bodies

• Water covers three-fourths of the Earth's surface.
• Much of the Earth's water is unusable.
• Not all water on Earth is available for use.

Water Distribution in Percentages

• Oceans contain 97.3% of the world's water, which is saline.
• Ice caps hold 2.0% of the total water and this water cannot be used
• Ground water accounts for 0.68% of the total water.
• Fresh water lake reserves comprise 0.009% of the total water.
• Inland seas and salt lakes make up 0.009% of the total water.
• The atmosphere contains 0.0019% of the total water.
• Rivers contain 0.0001% of the total world's water.

Global Fresh Water Scarcity

• Only a small fraction of the world’s total water is fresh and accessible for use.
• Water scarcity is an issue
• Conserving water is crucial.
• Potential water scarcity in the next 50 years could cause mass conflicts.

Major Global Water Bodies

• Major oceans: Arctic, Atlantic, Pacific, Indian, Southern (Antarctic).
• Seven oceans result from sub-dividing the main four.
• Major rivers: Amazon (South America), Mississippi (North America), Nile (Africa), Ganga and Brahmaputra (India), Yangtze and Huang He (China), Darling (Australia).
• Smaller bodies include: Caspian Sea, Dead Sea, Black Sea, Mediterranean Sea, Red Sea, Arabian Sea.

Ocean Circulation

• Ocean water is continuously moving, unlike relatively stable ponds and lakes.
• Ocean water moves due to waves, tides, and currents.

Waves Formation

• Waves form when wind pushes water, causing it to rise and fall.
• Constant pushing of water to cause the wave
• Stronger winds result in stronger waves.

Destructive Waves

• Strong winds create larger, more destructive waves.
• Earthquakes, volcanic eruptions, and underwater landslides can cause significant ocean surges.
• Strong waves can cause destruction, and body submersion

Tsunamis: Devastating Wave Events

• Tsunamis are large tidal waves originating from undersea seismic activity, leading to massive destruction.
• Tsunamis originated in Japan.

The 2004 Indian Ocean Tsunami

• The 2004 tsunami was caused by an earthquake with a magnitude of 9.0 on the Richter scale off the western coast of Sumatra, Indonesia.
• The Indian plate subducted under the Burma plate, triggering the earthquake and subsequent tsunami.
• The 2004 Sumatran Quake caused waters above to vibrate, shifting and triggering the tsunami in the Indian Ocean
• India's southernmost point, Indira Point, was submerged due to the tsunami.
• The tsunami affected coastal areas of Andhra Pradesh, Tamil Nadu, Kerala, Puducherry, and the Andaman and Nicobar Islands.
• There were over 10,000 deaths and 100,000 displacements.

Predictability of Tsunamis

• Tsunamis can be predicted 3-4 hours in advance, allowing time for evacuation and safety measures.
• Elephants and other animals have a natural early warning system and can sense impending earthquakes or tsunamis, causing them to behave erratically.
• In 2004, wildlife animals moved to higher ground.

The Indian Ocean Tsunami of 2004 Context

• The Indian Ocean is not typically hit by tsunamis unlike the Pacific Ocean.
• Lack of preparedness and knowledge among coastal dwellers of the Indian Ocean contributed to the high death toll in 2004 Indian Ocean tsunami.

The Pacific Ring of Fire

• The Pacific Ocean is prone to tsunamis due to frequent seismic activity and a high concentration of volcanoes around its rim, known as the Ring of Fire.
• Many geological boundaries are located around Ring of Fire, causing it to be a very destructive area.

Factors Increasing Tsunami Devastation

• The lack of monitoring systems and early warning systems in the Indian Ocean region made it difficult to respond effectively to the tsunami.
• Insufficient knowledge among coastal residents about tsunami warning signs, such as the rapid withdrawal of water from the coast, prevented timely evacuation.
• Effective evacuation is highly effective for surviving a tsunami in the event of rapid water withdrawal is observed.

Tides

• Tides are the rhythmic rise and fall of ocean water level that occurs twice a day.
• High tide occurs when water rises to its maximum height, while low tide occurs when water falls to its lowest level.

Causes of Tides

• Tides are caused by the gravitational pull exerted by the sun and moon on the earth's surface.
• The moon's gravitational pull has a more significant impact due to its proximity.

Spring Tides

• During the full moon and new moon phases, the sun, moon, and earth align.
• This alignment causes a stronger gravitational pull, resulting in higher tides known as spring tides.

Neap Tides

• The moon's gravitational pull influences the tides during its first and last quarter, drawing ocean water in diagonally and opposite directions, which results in lowered tides.

Benefits of Tides

• The constant water level change of high tides can aid navigation.
• High tides bring fish closer to the shore, aiding in fishing.
• Tides generate electricity using tidal power plants via collected water (high tide) that rotates turbines during both collection and recession, and ultimately rotation.

Ocean Currents

• As waves fluctuate the oceans surface, ocean currents fluctuate the stream of water.
• Ocean currents are streams of water flowing constantly on the ocean surface in definite directions.
• Ocean currents are also known as "Waterby's" : Stream are also known as "Waterby's"

Warm and Cold Ocean Currents

• Warm ocean currents originate near the equator and move towards the poles, being equatorially powered.
• Cold ocean currents carry water from polar regions to lower latitudes/equator.

Factors Influencing Ocean Currents

• Wind near an area affects tides nearby
• Water levels influence tides because the water can disperse to lower water levels
• Denser waters sink, displacing less dense water.

Global Ocean Currents

• Examples of global ocean currents include the Brazilian Warm Current and the Benguela Cold Current.
• Southern Hemisphere ocean currents tend to have more precise direction due to less landmass interference.
• Northern Hemisphere currents have less directional strength due to greater land interference.

Confluence of Warm and Cold Currents

• The meeting point of warm and cold ocean currents is beneficial for fishing because the water allows fishes to breed.
• Examples of meeting points: Waters around Japan, the Falkland Islands

Ocean Currents: Key Terms

• Salinity
• Tsunamis
• Dead Sea

Key Terms for Section (Ocean Currents)

• Salinity refers to the amount of salt in grams present in 1,000 grams of water, measured in parts per thousand with an average of 35 parts per thousand.

• A tsunami, also known as a "harbor wave" in Japanese, is caused by an earthquake under the sea.

• Each wave can devastate entire harbors when occurring

The Dead Sea

• The Dead Sea, located in Israel, has a salinity of 340 grams per liter.
• People can float in its extremely dense waters.
• The Dead Sea's waters are extremely dense, allowing bodies to float.

Wave Formation

• Waves are formed when winds scrape across the ocean surface.
• Stronger winds make stronger waves.

Water Cycle

• This is the process by which water consistently changes form to ocean, land, and atmosphere

Warm Oceans

• Located near the equator

Rhythmic Ocean Rise

• Can be described as "tide"
• Can be attributed to how much gravitational pull moon and sun is exerting

Matching Key Terms and Definitions

• Caspian Sea is the largest lake.
• Tide is the periodic rise and fall of water.
• Tsunami is a strong wave that can be triggered by seabed earthquakes.
• Ocean current is a stream of water moving along a definite path.