Services - Education - Tools of the Trade - Ambient Temperature Devices
Ambient temperature is the temperature of an area or room temperature. We want to know what the ambient temperature is so we have a base for the readings we take throughout an investigation. Itís useful to know, for example, that the average room temperature was 70 degrees the entire time we were conducting an investigation. Knowing this, we can be alert for spots that differ from that base reading.
We use basic home weather center instruments that you can get at your local department store to collect this data. While most come with a base unit and one remote, the number of remote units used can usually be increased. The base unit will give the temperature reading of the area around it and some will also give humidity and barometric pressure readings for that area as well. They will also give a temperature reading from the remote unit(s) and in some cases the humidity reading from the remote(s) too. Our oldest two models are the Springfield Precise Temp units and our newest model is from Oregon Scientific.
The oldest Springfield model we have consists of a base unit with a 4-foot wire attached with a temperature sensor at the end. It will give a temperature reading from the area around the base unit and a reading from the sensor at the far end of the wire. The sensor on the end of the wire is useful when you need to get a reading but canít get into an area or donít feel comfortable going into an area. The wire can be tossed into a crawl space, for example, and you can get a reading without having to physically go into the space.
The other two versions are very similar in appearance, but the newer Oregon Scientific model gives us a variety of information other than just temperature readings. They both consist of a base unit and several remotes. Each base unit can receive readings from two remotes. The remote units can be placed around a room to ensure that the entire room is at a uniform temperature. The older of the two models will give us the ambient temperature readings from around it. Its remotes can be placed up to 100 feet away. The newer version gives a humidity reading from both the base unit and the remote. The base unit also gives a barometric reading, shows the phase of the moon, and connects to an atomic clock. These extra bells and whistles are interesting considering some of the theories about ghosts and how the environment affects their manifestation.
The major drawback to these types of temperature recording devices is that they are very slow. The sampling rate for the three types we have is probably about one reading every minute. This is only good for making sure that you have a constant room temperature throughout the investigation to compare against your other readings.
To record sudden drops in the ambient temperature you need to use a thermocouple. This is a device that records the temperature by reading molecule movement between two wires made from different metals. These very sensitive devices have a range of several hundred degrees below zero to close to a thousand degrees above, depending on the type of probe used. They also will take two to three readings per second rather than one per minute. This gives you the ability to sweep a room and know right away if you are getting a temperature change. The key to using this device is to sweep the room periodically in a uniform manner to see if you are getting the same temperature reading as your weather center readings. You must perform a uniform room sweep so that you can get a reading from the entire room since you never know where you might come across a cold spot. Thermocouples are quite a bit more expensive than the weather stations but can be an integral part of an investigation. When used together, they increase the chance of finding any temperature variations that might appear.