1. Meteo 3: Chapter 1 Tools and basic terms we use to describe the weather Read Chapter 1

2. Terminology  Atmosphere: The envelope of air surrounding the earth –Includes gases, clouds and particles –Relatively thin  Meteorology: The study of the physics, chemistry, and dynamics of the atmosphere  Weather: The state of the atmosphere  Climate: describes prevailing weather conditions in a location in terms of averages/extremes over long periods

3. Atmospheric Gases  Permanent Gases- constant concentration  1) Nitrogen- 78.08%  2) Oxygen- 20.95%  3) Argon- 0.93%  4) Neon- 0.0018%  Variable Gases- variable concentration  1) Water Vapor- 0-4%  2) CO 2 - 0.038%  3) Methane-.00018%  4) N 2 O- 0.00003% Table 1.1 Grenci/Nese

4. Toolbox  Need to know when, where, what and how much we are referring to with respect to the weather!  Easier to communicate about the weather when we have standards for these  Where -> geography, topography, latitude/longitude  What -> e.g. temperature, pressure  When -> standardized time, timescales  How much -> statistics, UNITS

5. Political Map: Know Your States!  Show boundaries made and used by humans

6. PA Topography  Physical Maps: Show natural features –Important b/c earth’s surface influences flow of air

7. Latitude & Longitude  Latitude lines run parallel with equator  Longitude lines run pole to pole

8. Earth divided by Latitudes  Tropics lie between 23.5ºN (Tropic of Cancer) & 23.5ºS (Tropic of Capricorn)  From 23.5º-30º in each hemisphere = subtropics  Polar regions lie poleward of 66.5º  Mid-latitudes located between polar regions and subtropics

9. A Standardized Time Scale  8:00 am here is not 8:00 am in Chicago, Ulaanbaatar or Ouagadougou  Zulu-Time (Z) or Coordinated Universal Time (UTC) = time scale all weather observations are reported in…represents local time on Prime Meridian –Ranges from 0-24 hrs –Eastern Time Zone is 5 hrs behind UTC, 4 hours behind during Daylight Savings Time  E.g. 12Z = 7:00am EST or 8:00 am EDT

10. The larger a weather phenomenon, the longer it lasts!

11. Temperature  Temperature = measure of the avg. kinetic energy of a substance’s molecules –kinetic energy (KE) = energy associated with motion –High KEs correspond to higher temperatures –3 Scales to Describe Temperature –1) Kelvin- 0 K corresponds to temperature at which molecular motion ceases, known as absolute zero –2) Celsius Scale- used to give temperatures in all countries but US.…0ºC corresponds to ice’s melting point  ºC = K - 273.15 –3) 3) Fahrenheit= temperature scale used in US…32ºF corresponds to ice’s melting point  ºF = (1.8)ºC +32

12. Units  Scientists commonly use SI units => meter (m), second (s), kilogram (kg), and Kelvin (K) and scientific notation to represent numbers (e.g. 4.02 * 10 4 ) (e.g. 4.02 * 10 4 )  All kinds of tutorials on the web on how to convert units using ‘dimensional analysis’ or ‘factor label’  For example: http://www.ncsu.edu/felder-public/kenny/papers/units.html http://www.ncsu.edu/felder-public/kenny/papers/units.htmlhttp://www.ncsu.edu/felder-public/kenny/papers/units.html  And if you don’t learn how… if you don’t learn howif you don’t learn how

13. Statistics  Average (Mean)- sum of all observed values divided by number of observations  In meteorology, normals (averages) computed by averaging 30 years of data –Weather rarely conforms to “normals”  Range- maximum and minimum values  Probability of Precipitation (POP)- 70% chance of rain means a 7 in 10 chance that any point in the forecast area receives measurable rain

14. Weather Observations  In the U.S., surface weather observations taken automatically at ~1500 locations, mainly near airports…coordinated by government (FAA & NWS)  Weather conditions above the surface are measured using radiosondes- weather-sensing instruments carried aloft by weather balloons –Upper-air obs. are made at fewer spots (~100 in North America) and less frequently (2 times/day) than surface obs. –Sparse upper-air network limits predictive capabilities

15. Displaying Weather Data: The Station Model  CD from Grenci/Nese has cool interactive tool to make and modify station models, let’s take a look

16. So, what’s the temperature trend here?

17. Eliminate the extraneous data…

18. How about contours?

19. Isoplething  Isopleths connect points of equal value on a weather map –Isotherms = lines of equal temperature –Isobars = lines of equal pressure –Isotachs = lines of equal wind speed  Helps forecasters see patterns in data and estimate values at places where observations are not taken

20. How to Contour  Java applet from University of Wisconsin http://cimss.ssec.wisc.edu/wxwise/contour/  Isopleths that close in on themselves represent a maximum or minimum of a quantity  Usually drawn at equal intervals  Lines are neat/smooth, don’t cross or fork  More direction given in Grenci/Nese, p. 18-21 and in lab

21. Gradients  Gradient- A change in some quantity over a distance –Ex. Ski slopes –The larger the change over a given distance, the larger the gradient –Large gradients indicated by tightly packed isopleths –Meteorologists focus on large gradients of temperature, pressure, etc. because they indicate areas of changing weather