and forecasts. For example: KBIX (Keesler Air Force Base, Biloxi, Mississippi), KJFK (John F Kennedy International  Airport,  New  York  City),  and  KLAX  (Los Angeles  International  Airport,  Los  Angeles,  California) are ICAO identifiers used both to identify the station and  weather  products  originated  at  the  station. Radio-navigation aids may be co-located at an airfield or be located some distance away from an airfield. These aids are identified by three-letter station identifiers.  In  most,  but  not  all  cases,  the  radio navigation aid identifier is the same as the airfield’s national station identifier. Converting Station Identifier To Location Overseas   ICAO   identifiers   may   be   cross- referenced  to  WMO  block/station  numbers  and latitude/longitude by using the weather station catalog. OPARS (U.S. Navy Optimum Path Aircraft Routing System) subscribers may use the OPARS Data Base computer  listing  of  location  identifiers  to  cross- reference identifiers. The OPARS Data Base is the most comprehensive listing of identifiers, and is available either as a set of computer printouts, or is accessible via the  OPARS  computer  bulletin  board. For all stations in North America and for selected Department of Defense overseas locations, FAA Order 7350.6, Location Identifiers, contains alphabetical name  to  identifier  cross-references  as  well  as alphanumeric  identifiers  to  name  cross-reference sections. The  listings  also  include  radio  navigation aids. The ICAO region identifier, K, is not considered in this publication. Latitudes/longitudes are not provided. For many countries, the DOD Flight Information Publications (En route), IFR Supplement (Country Name),  provide alphabetical listings of airfield names andnavigation aid names.  Each  airfield  listing  provides the  latitude/longitude,  station  elevation,  and  station identifier, the time zone of the airfield, communication frequencies, and navigation aid station identifiers and frequencies. REVIEW   QUESTIONS 4-12 Q8. What is the geographic definition of the tropics? Q9. Why are great circle routes generally shorter than straight line Mercator tracks? Q10.  Which  of  the  following  scales  would  show greater detail; a 1:100,000 scale chart or a 1:10,000  scale  chart? Q11. Q12. Q13. Q14. Q15. Q16. GRAPHIC ENVIRONMENTAL PRODUCTS LEARNING OBJECTIVES: Identify the terms used to discuss graphic meteorological and oceanographic products. Explain how legends are used to identify information presented on a graphic product. Discuss  how  history  is displayed  on  a  graphic  product.  Identify  the standard  representation  for  various meteorological  parameters  on  graphic  displays. Identify  each  element  in  a  plotted meteorological  report. What  federal  agency  is  responsible  for producing maps and charts for the U.S. military? What publication contains a listing of available weather  plotting  charts  and  hydrographic charts? What is the significance of a WMO block/station number ending with the digit zero? Where  can  a  complete  listing  of  WMO block/station numbers be found? What is the ICAO region identifier for the United States? What publication contains a complete listing of all station identifiers in North America? The majority of meteorological and oceanographic products  in  use  are  computer-produced  graphic products. While nearly all of these graphic products may be reproduced on paper as a hard copy, they are designed primarily to be used in an almost paperless environment directly on a computer video display. These  graphics  are  commonly  called  charts-a holdover from the time when everything was plotted on weather  plotting  charts  or  maps-referring  to  the geopolitical background used for location reference on graphic weather products. Many types of information may be transferred to the computer via radio, satellite link,  telephone  modem,  telephone  facsimile,  LAN,  or by mail or courier service on floppy or laser disk. The graphic products received by any of these methods may be in the form of digital data fields or actual graphics. Most of the graphics received are intended to be nothing more than "tools" for the forecaster to use to determine the state of the current environmental conditions or the anticipated state of conditions at some time in the future.