| APL Weather
Historical APL weather observations have been archived since June 13, 1996. These observations are updated once per month, usually within the first three business days of the new month. APL archived observations are available as:
APL Extreme Precipitation Statistics A table
of extreme precipitation statistics based on regional climatological studies performed at Cornell University is available for APL's location in Laurel, MD. The data in the table express extreme precipitation amounts corresponding to
"average return periods" for 15-minute, 30-minute, 1-hour, 2-hour, 3-hour, 6-hour, 12-hour, 18-hour, 24-hour, and 48-hour precipitation totals.
Click here to see this table.
APL's weather station is located just north of Building 47 across the road from the "Big Dish". (Click here for photos.) The anemometer is mounted to the top of a steel tower about 65 ft above the ground. The remaining sensors are attached to a pole just to the east of the tower. These sensors range from 8 ft to 11 ft above the ground. This station is intended to support various technical projects and daily Laboratory operations. The weather observations are also available to students in elementary, middle, and high schools throughout the region via modem transfer and Internet connection. Many of these schools have the same set of weather instruments as APL. You'll notice their observations are mentioned during TV weather reports on Ch. 7 (WJLA-TV) in Washington, DC and Ch. 2 (WMAR-TV) in Baltimore. Daily APL observation summaries are also sent each month to the National Weather Service and become part of their monthly Metropolitan Washington Climate Review for analysis of regional temperature and precipitation events. The weather station consists of a set of instruments that measure and automatically record the following standard meteorological variables:
Data
are recorded and archived at 15-minute intervals. To estimate the station barometric
pressure at APL from the reported sea level pressure, subtract 0.51" from the
displayed data.
The station has been surveyed to the following position:
To
view real-time APL weather observations, click here. The observations are updated every few seconds, so hit the "Reload"
button to get the very latest observations. Listed below is a compilation of useful physical data about APL.
The point of reference for APL's geographical location is the original 1954 geodetic survey marker located within the ellipse in front of Building 1. This reference point was surveyed at:
Plant
Engineering can provide more specific latitude and longitude coordinates for other
locations within APL's borders if more detail is required. Anyone who has walked around APL knows that the terrain is anything but flat. Plant Engineering maintains a list of the elevations of all building floors and rooftops. For instance, the highest and lowest points above sea level surveyed from all of APL's buildings are as follows:
In our hemisphere, magnetic compasses point to the magnetic north pole, not the geographical north pole or "true north." (The magnetic north pole is located in northern Canada at about 73° N latitude, 100° W longitude. This location varies very slowly over time.) Therefore, in the majority of locations in this hemisphere, the magnetic variation or angular difference between magnetic and geographic north is nonzero. For APL, the magnetic variation is approximately 10.5° west. This means that our compass here points in a direction approximately 10.5° west of true north. Therefore, true north is located about 10.5° east ("to the right") of where our compass points. |
