1. Lithosphere, atmosphere, hydrosphere Unit 2 A

2. Our Earth: Geologic Timescale The geologic time scale is a chronologic schema (or idealized model) relating to time that is used by geologists, paleontologists and other earth scientists to describe the timing and relationships between events that have occurred during the history of the Earth.chronologicgeologistsearthhistory of the Earth

3. Geologic Timescale The table of geologic time spans presented here agrees with the dates and nomenclature proposed by the International Commission on Stratigraphy, and uses the standard color codes of the United States Geological Survey.nomenclatureInternational Commission on StratigraphyUnited States Geological Survey

4. Geologic Timescale Evidence from radiometric dating indicates that the Earth is about 4.570 billion years old. The geological or deep time of Earth's past has been organized into various units according to events which took place in each period.radiometric datingEarthdeep time

6. Internal Planetary Processes Layers of the earth – Lithosphere Outermost rigid rock layer composed of plates – Asthenosphere Lower mantle comprised of hot soft rock Plate Tectonics- study of the processes by which the lithospheric plates move over the asthenosphere Plate Boundary- where 2 plates meet – Common site of earthquakes and volcanoes

7. Plates and Plate Boundaries

8. Types of Plate Boundaries Divergent Plate Boundary-2 plates move apart o Convergent Plate Boundary-2 plates move together (may get subduction)

9. Types of Plate Boundaries Transform Plate Boundary- 2 plates move horizontally in opposite, parallel directions

10. Earthquakes Caused by the release of accumulated energy as rocks in the lithosphere suddenly shift or break – Occur along faults – Energy released as seismic wave Focus- the site where the earthquake originates below the surface Epicenter- located on the earth’s surface, directly above the focus Richter scale and the moment magnitude scales are used to measure the magnitude

11. Tsunami Giant undersea wave caused by an earthquake, volcanic eruption or landslide – Travel > 450mph Tsunami wave may be 1m deep in ocean – Becomes 30.5m high on shore Magnitude 9.3 earthquake in Indian Ocean – Triggered tsunami that killed over 230,000 people in South Asia and Africa

13. Solar Radiation 69% of incoming solar radiation is absorbed by atmosphere and earth – Remainder is reflected Albedo – The reflectance of solar energy off earth’s surface – Dark colors = low albedo Forests and ocean – Light colors = high albedo Ice caps Also see envirobrief pg 113 o Sun provides energy for life, powers biogeochemical cycles, and determines climate

14. Temperature Changes with Latitude Solar energy does not hit earth uniformly – This is due to earth’s spherical shape and tilt Equator (a) High concentration Little Reflection High Temperature Closer to Poles (c) Low concentration Higher Reflection Low Temperature From (a) to (c) In diagram below

15. Temperature Changes with Season Seasons are determined by earth’s tilt (23.5°) Causes each hemisphere to tilt toward the sun for half the year o Northern Hemisphere tilts towards the sun from March 21- September 22 (warm season)

16. The Atmosphere Invisible layer of gases that envelopes earth (ex. if earth were a hard-boiled egg, then the atmosphere would be the thin membrane right under the shell) Content – 21% Oxygen – 78% Nitrogen – 1% Argon, Carbon dioxide, Neon and Helium Density decreases with distance from earth Shields earth from high energy radiation

17. Atmospheric Layers Troposphere (0-10km) – The “WEATHER MAKER” – 75-80% of the mass of the earth’s air found here – 78% nitrogen, 21% oxygen Minor components – H 2 O = 0.01% ( poles ) – 4% ( tropics ); Ar = 1%; CO 2 = 0.037%; trace amounts of other gasses – Temperature decreases with altitude *Stratosphere (10-45km)* Similar composition as troposphere but less volume – Less H 2 O and more ozone O 3 – Temperature increases with altitude- very stable Stratospheric ozone produced when O 2 interacts with UV radiation and forms O 3 “Global sunscreen,” ozone keeps 95% of UV radiation from reaching surface Mesosphere (45-80km) – Temperature decreases with altitude

18. Atmospheric Layers Mesosphere (45-80km) – The mesosphere extends from 50 to 80km in altitude with very sparse atmosphere, accounting for only about 0.1 percent of the mass of the atmosphere as a whole.

19. Atmospheric Layers Thermosphere (80-500km) – Gases in thin air absorb x-rays and short-wave UV radiation = very hot – Source of aurora Exosphere (500km and up) – Outermost layer – Atmosphere continues to thin until converges with interplanetary space

20. Atmospheric Circulation Near Equator “Hadley Cells” – Warm air rises, cools and splits to flow towards the poles – ~30°N&S sinks back to surface – Air moves along surface back towards equator This occurs at higher latitudes as well – Moves heat from equator to the poles

21. Surface Winds Large winds due in part to pressures caused by global circulation of air – Left side of diagram Winds blow from high to low pressure – Right side of diagram Low Low Low High High High High

22. Surface Winds: Trade Winds The trade winds (also called trades) are the prevailing pattern of easterly surface winds found in the tropics near the Earth's equator 0 °-30 ° north and south prevailing pattern easterlywindstropics equator Blow from N.E. in the northern hemisphereand S.E. in the southern hemisphere Low Low Low High High High High

23. Surface Winds: Westerlies o The Westerlies lie between 30° - 60° north and south o They blow from the S.W. in the northern hemisphere and N.W. in the southern hemisphere

24. Surface Winds: Polar Easterlies o The Polar Easterlies lie between 60° - 90° north and south o They blow from the N.E. in the north pole hemisphere and S.E. in the south pole

25. Coriolis Effect Earth’s rotation influences direction of wind – Earth rotates from East to West – Deflects wind from straight-line path Coriolis Effect – Influence of the earth’s rotation on movement of air and fluids – Turns them Right in the Northern Hemisphere – Turns them Left in the Southern Hemisphere

26. Coriolis Effect Visualize it as a Merry-Go-Round (see below)

27. Global Ocean Circulation Prevailing winds produce ocean currents and generate gyres Example: the North Atlantic Ocean – Trade winds blow west – Westerlies blow east – Creates a clockwise gyre in the North Atlantic Circular pattern influenced by coriolis effect

28. Global Ocean Circulation Trade winds Westerlies

29. Position of Landmasses Very little land in the Southern Hemisphere Large landmasses in the Northern Hemisphere help to dictate ocean currents and flow

30. Vertical Mixing of Ocean waters account for deep (cold) and shallow (warm) currents

31. Ocean Interaction with Atmosphere- ENSO El Niño-Southern Oscillation (ENSO) – Def: periodic large scale warming of surface waters of tropical eastern Pacific Ocean Alters ocean and atmospheric circulation patterns Normal conditions- westward blowing tradewinds keep warmest water in western Pacific ENSO conditions- trade winds weaken and warm water expands eastward to South America – Big effect on fishing industry off South America

32. ENSO Climate Patterns The white areas off the tropical coasts of South and North America indicate the pool of warm water.

33. Weather and Climate (defined) Weather – The conditions in the atmosphere at a given place and time – Temperature, precipitation, cloudiness, etc. Climate – The average weather conditions that occur in a place over a period of years – 2 most important factors: temperature and precipitation – Earth has many climates

35. Land Masses can affect Weather: Ex. Rain Shadows Mountains force humid air to rise Air cools with altitude, clouds form and precipitation occurs (windward side) Dry air mass moves down opposite leeward side of mountain

36. Severe Weather: Tornadoes Powerful funnel of air associated with a severe thunderstorm Formation – Mass of cool dry air collides with warm humid air – Produces a strong updraft of spinning air under a cloud – Spinning funnel becomes tornado when it descends from cloud Wind velocity= up to 300mph Width ranges from 1m to 3.2km

37. Severe Weather Tropical Cyclone (a.k.a. Hurricanes) Giant rotating tropical storms Wind >119km per hour Formation – Strong winds pick up moisture over warm surface waters – Starts to spin due to Earth’s rotation – Spin causes upward spiral of clouds Damaging on land – High winds – Storm surges