Earth Systems

Things to think about

• Look at the world map1. Earth’s surface is not smooth. What do you

think causes variations in its surface?2. Is the Earth changing? List any evidence

(features or processes) that it is or is not changing.

3. What changes might occur to Earth’s surface 1. On a time scale of 100 years2. On a long time scale (10,000 – 1,000,000s)

USGS recent earthquakes

• Recent Earthquakes

• http://earthquake.usgs.gov/earthquakes/– The above link is to recent earthquakes

• What does the pattern of earthquakes and volcanoes suggest?

• How about the shape of the continents?

Tectonic plates

Animation: breakup of pangea

• http://www.classzone.com/books/earth_science/terc/content/visualizations/es0806/es0806page01.cfm?chapter_no=visualization

Structure of the Earth

Heat: where did it (does it) come from?

How do scientists knowabout the Earth’s structure?

• One way: earthquake waves that pass through the Earth and over the Earth’s surface– P waves (compressional, primary)– S waves (shear, secondary)

• Model

Plate boundaries

More evidence ofcontinental drift

• The colored bands represent where fossils of different critters and plants have been found.

• They span two or more continents.

• These creatures do NOT swim—or they are freshwater animals—so the continents must have been connected

Convection in the mantle

• http://www.classzone.com/books/earth_science/terc/content/visualizations/es0805/es0805page01.cfm?chapter_no=visualization

• Show the mantle model

Sea-floor spreading

• Mid-ocean ridge

• Diverging plate boundary

• How do we know?1. Prediction about age of sea floor

2. Magnetic reversals

3. It’s still spreading!

What does it mean…• To refer to the Earth as a system?

• Think ``machine’’ versus ``parts’’

Parts of the earth system

• Lithosphere (geosphere)

• Hydrosphere

• Atmosphere

• Biosphere

Open vs closed system

• Open: exchanges energy, matter, and/or information with other systems

• Closed: isolated and self-contained

• Is the Earth open or closed?– Energy?– Matter?

Hydrosphere

•

What happens to water

• With one partner, sketch out where you think water goes.

• Start with water in the ocean.

Water cycle

• Nasa's water cycle movie

Ocean water

• 96.5 % H2O by mass

• Remainder: various salts [35 parts per thousand]

• Temperature:– Warmer near the surface– Deep water (below ~1000 m) is equally cold

• Density:– Colder, saltier water is denser = deep water

Salinity patternsnumber is “parts per thousand”

•

Ocean currents

• Water flows horizontally

• Causes?– Surface: wind– Deep: density differences – salinity,

temperature

• Ocean conveyor - YouTube

Vertical movements

• Upwelling– Deep, cold water rises to replace surface

waters that flow away– Brings nutrients to surface– Site of rich fisheries

Freshwater

• Review: Where is the freshwater on Earth, and in approximately what percentages?– Ice caps, glaciers: 69 %– Aquifers: 30 %– Surface water: 0.9%– Atmosphere (and biosphere): 0.1%

Aquifers

• Rock layers below the surface of the earth that are porous and hold water.

• Water moves through an aquifer just as water moves in a river.

• See All the Water in the world, Google Earth

Aquifer

•

How water moves in aquifers

• In a word:– SLOWLY!

• Depends on the size of the pore spaces. – Smaller spaces mean slower flow

• At the other extreme: Large ``pore’’ space of a cave might have a river run through it

Aquifers

• Supply drinking water

• Anyone who has a well gets water from an aquifer

• About HALF of all Americans get most of their water from wells

• RECHARGE is key—the infiltration of water back to the aquifer

Aquifers

• Is the water clean?• Water moving through pore spaces of rock

or gravel is naturally filtered– ``coffee filter’’ keeps coffee grounds behind

• Dissolved chemicals can contaminate an aquifer and water pumped from its wells.– The filter doesn’t prevent the ``coffee’’ from

going through

•

What is this picture?

•

• >97% of the water flowing into Lake Mead comes from snow melt and rain—runoff—in the Rocky Mts, the source of the Colorado R.

Lake Mead

Lake Mead water levels

• http://www.arachnoid.com/NaturalResources/

US drought monitor

• http://www.drought.unl.edu/dm/monitor.html

The atmosphere

Where did the atmosphere come from?

• May have developed from gases released by volcanoes.

• This is Kilauea in Hawaii.

• Early atmosphere very different from today.

• NO O2, but H2O, CO2, CH4, HCl

Composition

• Nitrogen – 78 %• Oxygen – 21 %• All the rest???

– Carbon dioxide, methane, CFCs,

• Water vapor is variable, from 0 to 4 %

Structure

• 4 major layers• Troposphere: where the

weather is• Tropopause: jet stream• Stratosphere: ozone

layer• 99% of the total mass of

the atmosphere is below 32 km

• Temp. drops 5-10 C every 1 km in troposphere

Impact of air density

• Where is air densest? Where is it least dense?

• How does this affect a batted baseball?

• http://profhorn.meteor.wisc.edu/wxwise/baseball/homerun.html

• NOT true any longer: air conditioners and refrigerators no longer contain CFCs

• BUT: CFCs last a long time in the atmosphere (decades) so these gases are still doing damage.

Troposphere

• Our sphere• Weather• Notice: patterns

– Temperature– Winds

• Layer ends when temp. no longer varies with height = tropopause

•

Water cycle

• Connects ocean

and atmosphere • Key pt: what

happens in the atmosphere depends a lot on what happens in the ocean

Solar energy

• • Energy from sun• Some absorbed by

gases (O3, H2O)• Some reflected by

clouds and by the Earth’s surface

• Last is called albedo

albedo

• Notice snow, water, and clouds

• What feedback effects would you expect from melting of ice caps?

•

Energy transfer

•

Energy transfer

• Simplified earth: slow rotation to east, no interaction of oceans and land

• Sun warms equator, air rises, spreads north and south

• Cold air at poles sinks and replaces• Air deflected by rotation, to right in N

hemisphere, to left in S hemisphere– Coriolis effect