Hydrologic Cycle

(The flow of Earth’s waters)

Objectives

• To be able to summarize Earth’s hydrologic cycle.

• To be able to illustrate the hydrologic cycle. • To be able to discuss current issues related to

the Earth’s hydrologic cycle.

Vocabulary

1. Evaporation 2. Transpiration3. Evapotranspiration4. Sublimation5. Advection6. Condensation7. Runoff 8. Groundwater9. Infiltration (of groundwater)10. Precipitation11. Gulf Stream – not for hydrologic cycle assignment12. Desertification - not for hydrologic cycle assignment

Hydrological Cycle Video

• http://www.youtube.com/watch?v=oaDkph9yQBs

• Earth is unique, water exists here in three states:– Solid– Liquid – Gas

Earth’s Water

• Total volume of water on Earth is approximately 326 million trillion gallons. – That would be 20 decimals and (I looked this up)

would be 326 quintillions. • Question: if Earth’s water could fit into a

gallon container, what percent do you think would be available to us? – Think about the forms of water.

Answer to Previous Slide’s Question

• If Earth’s water could fit into a gallon container, only three tablespoons would available to us.

• The rest would be saltwater or freshwater stored in Antarctica or Greenland.

Major Glacial Ice Sheets

1. Antarctica – Earth’s largest freshwater sink.2. Greenland – Earth’s second largest

freshwater sink (with Antarctica, they play a major role in Earth’s water cycle).

3. Himalayas – Third largest ice sheet. Important due to its role in providing water for billions of people.

4. Southern Andes

Southern Andean Ice Field - Chile

Southern Ice Field – Chile/Argentina

Qori Kalis - Himalayas

Himalayan Ice Sheet – 3rd largest in World

Khumbu Glacier (Everest in the background)

Greenland Ice Sheet

Antarctica

Antarctica

Glacier National Park – Montana (Our own backyard)

It has been estimated there were approximately 150 glaciers present in 1910 when the park was established. In 2010, we consider there to be only 25 glaciers larger than 25 acres remaining in GNP.

Glacier National Park

Diagram – Hydrologic Cycle• Advection - the transfer of heat or matter by the flow of a fluid, esp.

horizontally in the atmosphere or the sea.

Classroom Assignment

• Illustrate the hydrologic cycle – you can find good examples of the hydrologic cycle in this PowerPoint or via Google Images. – Identify all of the different components of the

cycle.• The components are the 10 vocabulary words listed

above.

– Indicate how they are related via your illustration.• You will hand in your labeled illustration along with a

definition for each of the 10 vocabulary words.

Changes in Hydrologic Cycle

Examples: change in Gulf Stream and desertification

Gulfstream

Gulfstream Infrared Satellite

How the Gulfstream Works• Of all the ocean currents, the Gulf Stream is one of the

strongest. It brings warmth to Europe and North America.

• Surface water in the north Atlantic is cooled by winds from the Arctic.

• It becomes more salty and more dense, which makes it sink to the ocean floor.

• Cold water then moves towards the equator where it slowly warms.

• To replace all this cold water, the Gulf Stream moves warm water from the Gulf of Mexico to the North Atlantic.

Think of Gulfstream as a ConveyorYou can think of the Gulfstream as a massive water conveyor belt. Warm water flows north over the dense cold water that flows south. The warm water replaces the cold creating the current.

How the Gulfstream Works

• Could global warming affect the Gulf Stream?• At the end of last Ice Age (10,000 years ago),

huge amounts of ice melted.• Because of the new freshwater, the water in

the North Atlantic became less salty. • The ocean water in the North Atlantic was

less dense, and did not sink. • This caused the Gulf Stream to shut down.

How the Gulfstream Works

• Temperatures in northwest Europe fell by 5°C in just a few decades.

• Something similar could happen today: an increase in global temperatures and precipitation could add a lot more freshwater to the north Atlantic.

If the Gulfstream Shuts Down• A reduced Gulf Stream could lower

temperatures in northwest Europe and northeast US.

• However, there is debate over whether the Gulfstream shutting down would protect northwest Europe or northeast US from elevated temperatures from global warming.

• Major ecological effects on marine life – and potential for major economic losses.

Gulfstream

• Where is the Gulfstream?• How does the Gulf Stream current work?– What is the mechanism that moves the water?

• What is the effect of the Gulf Stream?• What might change the Gulf Stream?

Desertification - Honduras

Desertification – as it progresses

Desertification

Not just a third world problem• Dust bowl – southern plains

High Water Stress Areas

How would you define desertification?

• Take a minute and think about desertification.• With the pictures you have seen, define

desertification.• Formal definition: "the process of fertile land

transforming into desert typically as a result of deforestation, drought or improper/inappropriate agriculture“

• In some cases desertification can be stopped and “revert back” to normal state.– The ecosystem changes need to be halted.

Question

• Can desertification cause climatic changes?– What might those changes be?

• How could the hydrologic cycle be affected locally? – What would happen to the evaporation?– Transpiration?– Condensation?– Precipitation?– Infiltration of water to the water table?