Physics of Weather

1. Physics of Weather Presented by: Taylor, Anna, & Kirstie

2. Introduction • All weather can be predicted and understood through physics. • Weather can never be 100% accurate because of all of the variables accounted for. • We’re now going to explain three types of natural disasters…

3. Earthquakes

4. Why do Earthquakes happen? • The Earth is like a gigantic puzzle, it’s made up of many pieces • These pieces are called tectonic plates • In 1915 Alfred Wegener proposed the idea of continental drifts as a way to explain the findings of similar fossils across lands separated by entire oceans. • This idea was not widely accepted until the 1960s and this is when the concept of tectonic plates caught on

5. A map of the Tectonic Plates which make up the Earth's crust

6. A map of earthquake activity

7. Earthquakes • The ground beneath us is constantly moving • Below the surface is warm molten rock and it’s movement is governed by convection • The hotter rock near the core of the Earth is less dense and it moves upwards, as it cools down it becomes denser and sinks down • These currents are what slowly propel the tectonic plates

8. Earthquakes • These interactions between plates build up elastic strain energy • Eventually the potential energy becomes too much for the plates to handle and the rocks "slip" in a sudden fast motion • The location of the fault where this slip occurs is called the hypocenter from which seismic waves spread throughout the surrounding area • These are the waves people tend to feel during an earthquake

9. Earthquakes • Tectonic plates are in constant motion and rub against each other • They can move at a rate of millimeters per year • While at other times, the accumulated strain is released in earthquakes with a slip rate of meters per second

10. Earthquakes • These seismic waves radiate in all directions from where the energy was released underground, this is called the focus • Directly above ground is the theearthquake’s epicenter • This is where the earthquake will be the strongest

11. Haiti, January 12, 2010 7.0 magnitude earthquake

12. Japan, March 12, 2011 8.9 magnitude earthquake

13. Earthquakes • The result can be a slight tremor that is not even felt or can be a full blown earthquake causing terrible damage • The majority of earthquakes happen along the tectonic plate boundaries, although most are so weak they go unnoticed

14. Earthquakes • Can earthquakes be predicted? • The answer is no • Scientists are unable to issue an advanced warning for evacuation, however they do occur in predictable locations along fault zones • For places with a high rate of historic activity, the chance that a quake will hit in a future period of several decades can be quite high • According to Thomas Jordan, director of the Southern California Earthquake center, there are models that say within the next 30 years there is a 38% chance of an earthquake in southern California of a 7.5 or greater magnitude • But using the same model to predict an earthquake within the next week the chance drops to .02%

15. Earthquakes • In order to predict earthquakes scientists need reliable precursors. If any such precursors do exist, scientists have been unable to find them. • Seismologists have studied a variety of potential signals, such as increases in radon gas concentrations, changes in electromagnetic activity, foreshocks signaling a larger quake, warping or deformation of the Earth’s surface, geochemical changes in groundwater, and even unusual animal behavior before an earthquake – all have been unsuccessful

16. Earthquakes • Researchers are continuing to look at changes in electromagnetic signals prior to major earthquakes as a precursor • The approach is buoyed by the work of Friedemann Freund at the NASA Ames Research Center in California. • He has shown that compressing a rock can lead to the formation of positive electrical charges in the earth that could account for unusual electromagnetic signals prior to an earthquake…this research is still ongoing

17. Tornadoes

18. Tornadoes • Definition: a localized, violently destructive windstorm occurring overland, especially in the Middle West, and characterized by a long, funnel-shaped cloud extending toward the ground and made visible by condensation and debris. • Strongest winds on the planet are within a tornado. • Around 1,000 strike the U.S. per year.

19. How do tornadoes form? • First, warm damp ground is required. • Needed are two different patches of air moving towards one another, with warm air low and cold air high. • The warm air then rises, causing the cold air to take its place down low. This causes the spinning patch of air on the ground. • They always begin in a storm because of the air movement already.

20. Formation continued… • Interactions between air at different altitudes causes storms, lightning, rain, air circulation, and strengthen the rotating updraft. • A column of spinning air can form, which narrows and spins faster and extends higher into the storm.

22. Fujita Scale • Classifies tornadoes according to the damage they cause. • Scale from a F0 to a F6, judging by the amount of damage. • Problems: • Can only be measured after the tornado is gone and the damage is assessed. • Cannot be measure if it results in little damage.

23. Bernoulli’s Principle • The Bernoulli effect contributes to the damage caused by violent storms by reducing the pressure above a roof and lifting the rough. • Definition: an increase in the speed of a fluid produces a decrease in pressure and a decrease in the speed produces an increase in pressure. • Roofs can be lifted in a tornado, unless they are firmly anchored.

25. Damage Caused

26. Hurricanes

27. Hurricanes • According to the National Hurricane Center, a hurricane is a rotating, organized system of clouds and thunderstorms that originates over tropical or subtropical waters and has a closed low-level circulation.

28. Hurricanes – Basic Information • Hurricanes are actually tropical cyclones • they are only given “hurricane” status once they reach a certain wind speed and if they form over the Atlantic and eastern Pacific Oceans • Depending on where they form, they are also called typhoons and cyclones • There are three peak months for hurricanes: August, September and October

29. Hurricane Categories • There are three categories of tropical cyclones depending on their wind speed. • Tropical Depression, has wind speeds of less than 39 mph • Tropical Storm, has wind speeds of 39-73 mph • Hurricane, has wind speeds greater than 74 mph

30. Hurricane Scale • Once the storm reaches hurricane status it is described on a scale from 1-5 • 1: 74-95mph, very dangerous winds, generally produces minimal damage. • 2: 96-110mph, extremely dangerous winds with extensive damage. • 3: 111-129mph, extremely dangerous winds with devastating damage. • 4: 130-156mph, extremely dangerous winds with catastrophic damage. • 5: Greater than 157 mph, same damage as a scale 4.

31. Hazards of Hurricanes • They typically produce strong winds, heavy rainfall and thunderstorms • Sometimes they produce tornadoes, huge waves and currents, inland flooding and storm surges which are an abnormal rise in water generated by a storm. • The strong winds turn everyday items into dangerous projectiles.

32. Hazards of Hurricanes

33. How do they start? • Hurricanes are like massive heat engines, they use the warm, moist air as their fuel to produce mechanical energy. • This is why they only form over warm waters near the equator. • As the warm, moist ocean air rises upward, it begins to cause an area of low pressure below. • Over time higher air pressure pushes into the low pressure area which causes the air in the low pressure areas to heat up and rise. • As the warm air rises it begins to cool off and form clouds.

34. How do they start? continued… • The newly formed clouds and wind spin and grow larger and stronger because they’re gaining energy from the ocean’s heat and evaporating waters. • Eventually the storm will rotate faster and faster, creating the “eye” in the center. • The eye has very low air pressure and is calm and clear in comparison to high pressure areas.

35. How do they start? continued… • The storm will continue across the ocean but eventually weaken once it strikes land since they’re unable to gain energy from the warm ocean waters.

36. Hurricane Structure

37. Random Facts About Hurricanes: • The amount of heat energy that is taken in by a hurricane is the equivalent of half the world’s electrical generating capacity. • Due to physics, hurricanes can be forecasted well in advance and allow people time to prepare. • Tropical Cyclones north of the equator spin counterclockwise, tropical cyclones south of the equator spin clockwise • This is because of the Earth’s rotation on it’s axis.

38. Conclusion • Now you have seen three types of weather that show how hard it is to predict what will happen and what caused it. • Again, we can try to understand the disasters by using physics, but it is still impossible to be 100% accurate.

39. References • http://www.physics.org/article-questions.asp?id=50 • http://nyusps.blogspot.com/2011/08/physics-behind-earthquakes_23.html • http://authors.library.caltech.edu/6698/1/KANrpp04.pdf • http://www.newscientist.com/article/dn20243-why-earthquakes-are-hard-to-predict.html • google.com/images • Merriam-webster.com • outreach.phas.ubc.ca/phys420/p420_04/sean • www.spsobserver.org/2011/the-physics-of-tornadoes.pdf • http://ocean.si.edu/blog/ingredients-hurricane • http://www.nhc.noaa.gov/outreach/presentations/2012_02nhcL311_hurricaneLifeCycleHazards.pdf • http://spaceplace.nasa.gov/hurricanes/