5-14 Weather To seafarers the state of the weather is of greater importance  than  it  is  to  most  people  ashore.  The elements affect us all at one time or another. They can be very  pleasant  or  they  can  be  devastating  for  all concerned.  As  the  POOW  you  will  have  to  know something about weather. Accurate weather forecasting may not be as vital today as it was in the days of sailing ships. However situations still arise when the safety of the ship and the lives of the crew depend upon the accurate reporting of and reacting to an approaching storm. In addition to helping you learn about the heavy weather bill, this section will present some of the POOW responsibilities concerning weather. HEAVY WEATHER BILL.—There is no weather bill to follow if the weather is nonthreatening. As the petty officer of the watch, you may be required to keep the weather log at the quarterdeck area. If you notice that the barometer has fallen .04 inch or more in 1 hour, notify the officer of the deck,  as  this  is  the  first indication of an approaching storm. Most of our weather information today comes from local sources, and they tell us of approaching storms. The heavy weather bill will be placed in effect during periods of actual or forecasted high wind and seas, hurricanes, typhoons, tidal waves, and so forth. To be effective, you must take the steps contained in the bill before heavy weather commences. You will probably be called upon to help the officer of the deck implement the heavy weather bill. You may be assisting the ODD with some of the following responsibilities: Keeping informed of the weather condition in effect and ensuring that proper preparations are being taken Stationing personnel to tend lines as appropriate Requesting  tugs  to  clear  any  ships  from alongside Ensuring that all service lines not actually required are removed from the ship Keeping the captain, executive officer, and command  duty  officer  informed  of  the  status  of preparations to get under way or cope with the storm if the ship is to remain in port If expecting a tidal wave (tsunami), having additional   mooring   lines   run   out   making   sure considerable slack is left in regular mooring lines; if necessary, having fenders placed between the ship and the pier More information concerning the heavy weather bill can   be   found   in   Standard    Organization    and Regulations of the U.S. Navy. ADDITIONAL WEATHER-RELATED RESPONSIBILITIES.—In addition to the assistance you may provide during heavy weather, you will have other POOW responsibilities concerning weather. Some of   those   responsibilities   are   the   measuring   of temperature, atmospheric pressure, and wind speed. You also must have a working knowledge concerning weather flags and pennants. Measuring Temperature.—You probably don't need to be told that a thermometer is an instrument for measuring  temperature.  The  ship's  thermometer  is usually located on the bridge, but on some small ships it is  located  near  the  quarterdeck  area.  Most  Navy thermometers are liquid-filled and practically all of them use the Fahrenheit (F) scale which is based on the freezing point of water being 32F and the boiling point being 212F. A thermometer must be read properly for you to obtain an accurate result. First, if you must handle it, be sure that you do not touch the lower part of the glass containing the liquid. The heat from your body can affect the height of the liquid column and give an erroneous temperature reading. Make sure that the top of the column is level with your eyes; otherwise, you will be reading a higher or lower graduation than the one actually indicated. Another  weather  device  that  you  must  use  to forecast the approach of a storm is the barometer. Measuring Barometric Pressure.—The aneroid barometer, as shown in figure 5-2, contains a small metallic cell, called a Sylphon cell, which encloses a partial vacuum. As atmospheric pressure increases, the