how do automotive rain sensors work?
139783
I assume you are talking about auto. windsheild wipers?\n\nI don't have specifics on brands of sensors, but they usually work using hydroscopic discs.\nthese discs are made from material that expands when wet. They are connected to a normally open electrical switch. When it rains, the discs expand, closing the switch and turning on the windshield wipers. As the discs dry out, the switch opens again, turning them off.
974802
ASOS The Automated Surface Observing Systems  uses an array of sensors to detect weather phenomena I.E.  Rain, Wind, Tempature, Lightning and other weather related information\n   Available technologies of the present day lightning detectors include: \n\na. Radio Frequency (RF) Detectors. These measure energy discharges from lightning.  They can determine the approximate distance and direction of the threat.  \n\nb. Inferometers. These are multi-station devices, much more costly than RF detectors. They measure lightning strike data more precisely. Usually they require a skilled operator.\n\n\nd. Atmospheric Field  Mill Monitors. These measure the potential gradient (voltage) changes of the earth's electric field and report changes as thresholds build to lightning breakdown values.  \n\ne. e. Optical Monitors. These can provide earlier warning as they detect cloud-to-     cloud lightning that typically precedes cloud-to-ground lightning.
76386
Since it measures air pressure it can be used for detecting changes in the weather as high and low pressure zones move across the planet. Another use for barometers is to measure changes in altitude. Most inexpensive altimeters are a barometer that is used to measure relative changes in air pressure in terms of change of altitude. (Radar and GPS altimeters do not work this way)
279308
There are two types of Traction Control. One system applies the brakes to a specific wheel when a sensor detects it slipping. The 2nd way is for the car to slow itself down by reducing the amount of fuel when it detects wheel slippage. Many cars with Traction Control use a both systems.
630328
A lot of Science and Maths goes behind such predictions. Data collected from satellites, weather balloons, planes and land based instruments is analysed for numerical patterns. These patterns are then processed and compared with findings of a particular time span when a certain amount of known rainfall occurred. In the end a forecast is issued.\n\nNowadays, the job is done by Super Computers but there still remains a large room for errors.
1149784
Because it doesn't freeze under normal weather conditions but still reacts to atmospheric changes.\n\n\n"Barometers are instruments that measure air pressure. The mercury barometer was developed in the 17th century. They are still used today, but many of today's barometers use aneroids to detect air pressure. (Related: How a mercury barometer works). \nTo make a record of the air pressure and how it's changing, and aneroid is connected connected with a device that records air pressure, making it an aneroid barograph. \nAn aneroid is a flexible metal bellow that has been tightly sealed after having some air removed. Higher atmospheric pressures squeeze the metal bellows while lower pressures allow it to expand. \nThe aneroid barograph consists of a slowly rotating cylinder with paper on it that can give up to a week's worth of air pressure records before new paper is needed. \nAs you can see in the graphic above, a pen at the end of a lever attached to the aneroid moves up and down according to pressure changes and records the pressure on the paper wrapped around the cylinder. \nThe aneroid barometer has some advantages over a mercury barometer because it is much smaller and can also record a week's worth of data. The aneroid barometer is the heart of altimeters used in modern aviation." http://www.usatoday.com/weather/waneroid.htm
185249
Don't listen to the other guy because it actually lowers!\nThe faster you go the pressure builds up and that airflow pushes down on the vehicle. MIKE
999967
We used to do it by wetting the ground or waiting until just after a good rain storm.... then a metal rod with a good insulated handle.... attach the negative side of a 12 volt car battery to a ground rod.... and attatch a wire and small rod to the positive wire... made sure you have on some good rubber boots.... and touch the small rod to the ground for just a couple of seconds... three or four.... and let it up.... it used to bring up alot of night crawlers in a hurry
754776
It measures the density of cumulative clouds. Good Luck !  :)
525590
radio-immune precipitation
348168
the mechanic is Doppler effect.\n\nthey send microwaves or some sort of electromagnetic waves and then they measure the frequency of the reflected wave and then they can determine the speed of a vehicle
1027903
I'm not completely sure, but I do know that the ring signals that the next day will be rainy. Perhaps it has something to do with an incoming front. Or a rise in humidity.
584475
Build Your Own Barometer \n \nWhat you need:\n• clear plastic cup\n• 2-liter plastic soda bottle\n• water\n• food coloring\n• marker\n\n\nWhat to do:\n1. This tool will work best if you put it together on a rainy day (when air pressure is lower). Pour a few inches of water into a plastic cup. Add a few drops of food coloring to the water. \n\n2. Place a plastic bottle upside down inside the cup. (It should fit snugly, but should not be airtight.) The mouth of the bottle must be below the waterline but not touching the bottom of the cup. Use a marker to note the water level on the side of the cup.\n\n3. Check the barometer after a couple of days. If the weather has gotten clearer, the water level in the cup should have fallen and the level in the bottle should have risen. \n\n4. The air pressure is what causes the change in water level. When the weather is clear, air pressure is higher, but when a storm is coming, air pressure drops. As the weather cleared up, the air pressure rose, and this pushed down on the water in the cup. Thus, the water level in the cup fell and the level in the bottle rose.\n\n5. As you watch the weather reports on the news, note what the weather forecaster says about the air pressure (or "barometric pressure"). If he says it will rise, does the water level in your homemade barometer also rise? What happens if he says the pressure is falling? \n\nLearning Benefits\n• develops understanding of air pressure\n• demonstrates the relationship between air pressure and weather\n• encourages testing of hypotheses
287818
UNFORTUNATELY IT WORKS, IS DIRECTLY CONNECTED WITH A SPEED SENSOR CONNECT TO THE OFFICER'S VEHICLE.  IT WORKS APPROACHING OR ON-COMING.  ANTENNA'S ON VEHICLES ARE DIFFERENT BUT DOWN HERE WE USE A ANTENNA WHICH APPEARS TO BE A SPOTLIGHT HOOKED OVER THE TOP OF THE WINDOW GLASS.  IT MAY BE AIMED UP OR DOWN THE ROAD.\n\nWORKS AS LONG AS THE VEHICLE IS IN SIGHT!\n\nDRIVE CAREFUL HEAR !
635370
It isn't easily automated. I mean you can't have a remote automated weather station that reports the humidity with a sling psychrometer, it requires manual operation.
1069269
Use RainX, it's really good about breaking up the drop of water so they very easily and quickly run off the windshield. It's not expensive either, you can find it at any autoparts store or even like Target, Walmart, KMart, etc.
66931
My vision isn't good enough to actually "look" through a raindrop, but I understand your question.  Raindrops are a lot like a lens.  In fact, a raindrop is a lens.  Every lens has a focal length based on its shape and material and when objects within the focal length, they are magnified.  Raindrops, however, have a very short focal length so anything you see through them will likely be beyond the focal length.  Objects beyond the focal length are not necessarily magnified, and in fact they are flipped.  It's much easier to understand with a ray tracing diagram.  I've provided a link to the slides my professor used in his optics lecture.  Slide 5 in particular should be of help.