Does PIR Motion Sensor Light Work In Cold Weather? Motion Sensor Light Cold Weather

Does PIR Motion Sensor Light Work In Cold Weather? Motion Sensor Light Cold Weather

PIR sensors detect Infrared Radiation (IR) combined with the apparent movement of the IR source.

If you look closely at a motion detector you will see a “bumpy” translucent plastic lens that sits in front of the actual IR sensor. The bumps are usually on the inside, so they may not be obvious.

A static, non-moving heat source will not trigger the sensor since it does not cross the “bumps” in the lens. When a heat source moves, the bumps raise and lower the IR level detected by the sensor. Circuitry in the motion detector measures the time between the high/low IR sensor readings. If the time period is short enough (a fast-moving hot object) then the circuitry triggers.

This setup prevents sunshine and most other man-made heat sources from accidentally triggering the PIR. The heat is evenly distributed across the PIR’s field of view so the signal does not vary much or change very slowly.

Now, to your question:

Where I live, it is common to have hot weather (close to body temperature) during a rain storm. Wind and rain can cause tree branches to move around. If the heat source is moved around by wind or masked by moving cold objects then the PIR would trigger.

Most people are not very good drivers and they become overcautious when it rains.

Most People don’t keep good wiper blades on their cars so they can’t see when it rains.

Most People don’t keep good tires on their cars so they tend to hydroplane in conditions that they normally wouldn’t if they had good tires, so they have to go much slower than necessary.

How do motion sensor lights work? In a dark environment, how can the motion sensor light detect movement?

The simplest uses infrared radiation emitted by warm-blooded animals. Humans belong to these specifications. In addition, the sensors that detect the heat of the human body are designed for the temperature of the heat range of the human body (about 37 °C) and ignore or are less sensitive to pets.

The next step of sophistication is by using ultrasounds to scan the area and to help the decision to do something with the light.

There is even more: the sounds produced by the people in the room.

For the use of PIR (Passive Infra-Red), the first enlisted above, if you move very slow (you see that in some movies) you can cheat on them. So if you enter an area with the light controlled by PIR then, after a few minutes, the light goes off if you stay still. So, there we go with some degree of sophistication.

There is even more. The newest light controllers (and cheapest, IMHO) use the microwave - the same frequency as some routers and microwave ovens 2.4GHz) to sense the presence of somebody in the room and power the lights.