Please turn on JavaScript and try again. Site Contents. Welcome Announcements. Welcome to the digital collection of unclassified issuances released by the: Secretary of the Navy. Chief of Naval Operations. Contact Information.
Thank you. Official Announcements. This is an Official U. Navy Web Site. It starts at the beginning of the fiscal year when Manual Issuance: An executive order, management directive, administrative circular, manual or other publication that announces policy, details procedures or guides, instructs or informs employees in their work.
An issuance may be directional, informational or procedural. Executive order : An issuance that announces the Governor's policies and programs. Executive orders are signed by the Governor. Executive orders can be revised or rescinded only by another executive order. Executive orders are published in the Pennsylvania Bulletin and Pennsylvania Code.
Management directive : An issuance that announces detailed policies, programs, responsibilities, and procedures that are relatively permanent. If instruments are not available, wind direction and speed should be estimated according to directions given in FMH No. The 8-inch nonrecording gage is the standard gage used at all NWS stations.
However, as a general rule, if 10 percent or more of the annual precipitation liquid and water-equivalent of solid occurs as snow and climatic summaries are prepared for the station, the station should be equipped with a weighing gage.
If a station is to make basic weather or synoptic observations and is to report precipitation amounts, it should be equipped with a gage capable of determining precipitation amounts to the nearest 0. An 8-inch nonrecording gage should be maintained as a backup for a weighing gage.
It should also be available to take core samples for determining the water equivalent of solid precipitation. No backup is required for the 8-inch nonrecording precipitation gage. However, a spare receiver funnel, measuring tube, and stick should be kept on hand. Alter-type snow shields should be used on gages in areas where 20 percent or more of annual precipitation falls as snow.
However, it is not necessary to shield tipping-bucket rain gages unless the gage is heated. Pyranometer and Pyrheliometer. These are radiometers used to collect information on the amount and distribution of solar radiation received at the earth's surface.
Sunshine Switch. This instrument is used to determine the duration and time of occurrence of the visibility of the sun's disk. Siting and Exposure of Equipment. Locate the RBC either in the vicinity of the ILS middle marker in the approach zone of the primary instrument runway or 3, feet from the approach zone of the primary instrument runway.
The projector and detector should be as near the middle marker as possible and be parallel to the approach path. However, it may be installed at an angle to the approach path if necessary because of terrain, obstructions, etc. To minimize interference, locate the detector as far as possible from strobe lights, other modulated light sources, radio transmitters, source of vibration, etc. It is desirable, but not necessary, that the detector be located at the same level or in line-of-sight of the projector.
A site along the approach path toward the airport from either the middle marker or a point 3, feet from the end of the primary instrument runway, or. A site on the airport near the approach end of the primary instrument runway which will not violate obstruction clearance criteria. If an RBC has a single detector and is to serve an airport permitting aircraft operations with visibilities of less than one-quarter mile, install the RBC on a foot baseline.
Otherwise, install single detector RBC's with a baseline between and 1, feet, but as near feet as possible. The inflation building for storing hydrogen or helium and the balloon release site must be readily accessible to the observer.
The release site should be relatively free of obstacles that might interfere with the balloon's ascent or obstruct the observer's view of the ascent of the balloon. Except in unusual circumstances, do not use hydrogen to inflate ceiling balloons unless it is also used at the station to inflate raob or pilot balloons. Where ceiling balloons are inflated within the office, use helium. If hydrogen is used , take extreme care when handling and storing this gas since it is extremely flammable.
Do not inflate balloons within the office quarters. The same safety rules given in chapter B for RAOB and pilot balloons also apply to the use of hydrogen for ceiling balloons. Before installing the ceiling-light projector, determine the desired baseline, i. When determining the baseline, consider the frequency of low visibilities, the most significant cloud heights, and the background lighting.
Frequent low visibilities and high background light tend to make a shorter baseline desirable. In general, the baseline should be around to feet. The baseline should be no shorter than one-third the most significant cloud height, and the maximum length should be no more than 1, feet. After determining the desired baseline, and with the standpoint convenient to the observer, locate the projector so that there will be a minimum amount of background light and obstructions along the baseline.
If possible, install the projector in the direction toward the runway most often used for instrument or bad weather approaches. If possible, isolate the projector from vehicle and pedestrian traffic. The site from which visual weather observations are made should ideally be the Airport Reference Point ARP to give representative indications of weather conditions in the areas of aircraft approaches, landings, and takeoffs.
Since this is not usually practical, the site should be as close to the ARP as possible, except in unusual circumstances, no more than 2 statute miles from the ARP. The site should have an essentially unobstructed view of:. Therefore, the published position should suffice for determining the location of the visual weather observation site. Runways to be abandoned or closed are not considered in this determination. The only time that a redetermination of ARP is necessary is when airport developments or changes are proposed.
Expose the visibility sensor so that it will render visibility that is as representative of the prevailing visibility as possible. Avoid placing the instrument in an area that is subject to very localized obstructions to vision or in an area that is frequently free of an obstruction to vision when it is present in the surrounding area.
For example, do not locate the sensor:. Locate sensors so they are free of jarring, vibration, and rapid temperature fluctuations. Avoid installing them ln a location where they will be exposed to direct sunlight, drafts from open windows or doors, warm air currents from heaters, or cool air currents from air conditioners.
Detailed instructions for installing barometers are given in the Manual of Barometry. Locate the sensors:. In considering possible sites, avoid areas where rough terrain or air drainage would result in nonrepresentative temperature data. Avoid swampy locations or other areas where water tends to collect and remain after precipitation and areas subject to artificial irrigation. Also avoid areas where frequent drifting of snow occurs.
At locations where the temperature sensors are to be mounted within an instrument shelter, position the shelter so that it opens to the north in the Northern Hemisphere with the floor 4 to 6 feet above the ground. In the case of remoted sensors not exposed in instrument shelters, e.
If the area is subject to large amounts of snow, install the sensors so that the height can be adjusted to a level 4 to 6 feet above the top of the snow. If, however, the temperature data are required primarily for a special purpose, that purpose should determine the exposure. For example, if the temperature affecting a low-lying crop is required, the temperature sensor should be exposed at the level of the crop, or if temperature and dew point affecting aircraft operations are required, the sensors may be exposed closer to paved areas than generally desirable.
It is essential that the temperature sensors have an unobstructed flow of air. Keep grass or other vegetation within feet of the sensors clipped to a height of less than 10 inches. The following gives a brief description of the siting requirements for wind sensors installed to satisfy the general requirement for wind data. These siting requirements do not apply to sensors installed for special purposes, e.
If the site is at an airport, it should be located near the center of the runway complex such that wind observations will be representative of conditions in the average lift-off and touch-down areas. The site should be relatively level. Small gradual slopes are acceptable but avoid ravines, bluffs, ridges, etc. The site should also be as far as practical from and, if possible, climatologically upstream from objects obstructing the free flow of air.
An exact definition of what constitutes good exposure is difficult to state.
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