Submitted by Eric Daniel
"All stations this net, this is Charlie Niner-Two, stand by for air temp and pressure update, over."
In Armor, weather updates are a critical element to the tank's fire control system. While the FCS can automatically sample some data, such as wind speed, inclination, and turret traverse rate, it can't tell what the ammunition temperature, air temperature, and barometric pressure are. In these cases it's up to the crew to manually enter this data. In the case of ammunition temp, this is simply a matter of reading the temp off the ammunition temp gauge, but getting air temp and baro pressure require outside assistance. In peacetime, this data can be had from the tower (C92) or the TOC, both of whom get the information from Range Control.
What do you do, though, if you're in combat, on the attack, and there is no tower, and there is no range control? In 1991 we learned that you "just run with it." The Army has published "fleet" values published in the back of the tank's TM (Technical Manual) for baro pressure and temperature for given months of the year and regions of the globe. Unfortunately, these values can be wildly off base.
Our solution was to invest $50 in a wall mounted "weather station" from the PX. The three instrument "station" had a clock, a thermometer, and a barometer, all bolted to a wood plaque which, conveniently, fit right behind the GPS "doghouse" and was visible through the TC's (tank commander) FUP (Forward Unity Periscope, the big vision block in the front of the TC's cupola.) With our handy dandy weather station we were able to enter in relatively accurate (the barometer was analogue while the FCC accepts inputs to the hundredths so some guesstimation was required) values for the air temp and pressure.
Well, times have changed, but the need for weather data has not. Fortunately, advances in technology have made portable weather stations cheaper, more accurate, more durable, and with a number of features ours didn't have.
The Coghlan's wireless weather station, for example is completely weather resistant, driven by a lithium battery, and is capable of sampling air temp, air pressure, humidity, heat index, and it can make local weather forecasts based on the previous 8 hours of sampling data. If you put the base unit in the ammunition compartment (hang the remote sensor outside) you can use it as a back up ammunition temp sensor as well.
Another option is the La Crosse Intelligent Forecast Station. This unit, in addition to the features offered by the Coghlan unit, is also capable of predicting frost, fog, and snow, as well as "real-time" weather forecasts based on a 12-hour data sample. The La Crosse unit also keeps time through an Atomic clock signal receiver, which makes it's time keeping extremely accurate.