Anemometer & Weather Station Placement Guide

What is the best way to mount a weather station and an anemometer? All sensors have their limitations and require proper placement for accurate results.

“Measure accurately or don’t measure at all” from the words of our founder Mr. Barani.  “Bad measurements give misleading results and lead to wrong conclusions.”

If you follow these simple rules, your weather station data will be as reliable as a professional’s.  Since most of us are limited in sensor placement by where we live, here are a few simple rules to follow for weather station placement, along with their explanations.

Practical rules for weather station placement

SIMPLE AND QUICK WEATHER STATION PLACEMENT GUIDE(Practical rules for weather station placement)
Instrument / Sensor / Atmospheric Property	Placement and mounting recommendations	Why? (The reasons behind each sensor placement rule.)
Anemometer (wind speed sensor) & Wind Vane (wind direction sensor)	Place anemometers at least 2x the height of any large hard object within a 50 meter (50 yard) radius.	Wind cannot flow through hard objects like houses. They heavily distort it since it must flow around them. A wind shadow of bad turbulent air is created behind objects, and wind speed and wind direction are distorted in front of them. If you mount an anemometer too close to an obstacle you will measure turbulence and not real quantifiable wind speed and wind direction. Measurements will be very chaotic, inconsistent, and for the large part, useless unless turbulence measurement was the intended purpose.
	Place anemometers at least 3 heights away from the closest tree. Dense trees require more distance, just like hard objects in the previous point.	Wind can flow through trees, but they slow it down. Trees cause wind shadows, though not as strong as houses do. Many times trees are tall, and placing anemometers above them is not practical. It is essential to give wind enough distance to speed up to its regular speed after it encounters a tree. It will also make sure that the wind shadow will only affect measurement from a very narrow wind direction band. Ideally, an anemometer or weather station will be placed at minimum 2X higher than nearby vegetation.
	Place a lightning rods around and above meteorological equipment and anemometers. Lightning rods protect equipment beneath and downwind of them.	As a rule, lightning rods protect sensors from direct lightning strikes if sensors are placed beneath and downwind of them. In fact and despite popular belief, lightning rods neutralize electrical fields that contribute to lightning. That is how they protect buildings, equipment, and infrastructure. They only attract lightning in strong winds where the ions created by their sharp tips are blown downwind quicker than they can neutralize the charge around them. At which point, they become the path of least resistance for lightning. The energy radiated from lightning can damage sensors many yards (meters) away. It is important to use proper lightning protection in all outdoor electronics and to maximize the distance of equipment from potential lightning impact points. Lightning rods protect sensors from direct lightning hits, but the radiated energy may still render sensor electronics useless. Lightning is unpredictable and dangerous. Always protect yourself and your equipment!
Humidity and Dew Point sensors	Place dew point & humidity sensors as far away as possible from pavement, buildings, trees, and ponds and no less than 2m (6ft) above ground.	Vegetation expels moisture; thus, any moisture sensors like humidity and dew point sensors in its vicinity will measure higher than actual readings. Place a hand near a good-quality humidity sensor, and humidity readings immediately rise. Ponds, wet sand and soil surfaces, wet pavement or houses, trees, grass, and all living things affect humidity around them. Thus it is very important to place humidity and dew point sensors in well ventilated or windy places.
Air Temperature sensors	High-quality temperature sensors require good solar radiation shields (white plates stacked on top of each other) and to be placed no less than 2m (6ft) above ground, away from walls, pavement, trees, and vegetation.	All objects heat up in the sun. 99% of them become much hotter than the ambient air around them, like a car on a sunny day. Air very close to hot objects heats up, thus placing a temperature sensor near objects in direct sunlight, will show artificially high temperatures. Hot objects radiate heat (infrared radiation). Above a car's trunk, one will not only feel warmer air but also heat radiating from it. The same is true of walls, trees, ground, pavement, fences, and all other objects warmed by the sun. It is essential to shield temperature sensors also from the heat radiating from nearby objects, the ground, or other sensors to prevent significant often overlooked measurement errors. Please note: Since relative humidity values are very sensitive to air temperature, humidity readings will be artificially low.
Rain Gauge (Precipitation sensor)	Industry-standard rain gauge placement is 1m (3ft) above ground and away from objects, which may shade it from rainfall on windy days. Placement in a location shaded from wind is very beneficial.	Most accurate precipitation measurement is on the ground where wind speed is always zero. Since critters can easily crawl into rain gauges placed on the ground and animals can use them as watering holes, 1m (3ft) height is a good compromise. At 1m height, wind can introduce higher errors into measurements since raindrops splatter into many small drops on impact with the rain gauge, some of which get thrown into the air. Wind can blow them out of the rain gauge to cause an increasing rain measurement error with wind speed.
Barometric Air Pressure Sensor	Wind speed affects air pressure measurement so placement of pressure sensors in a windless place is essential.	As air speeds up, its barometric (static) pressure is transformed into a dynamic pressure force that we feel on our bodies when standing in the wind. This pressure force is the same force that lifts airplanes and causes damage during hurricanes. As wind slows, moving air's dynamic pressure (energy) is converted back into static pressure, consequently a higher barometric pressure reading. Since wind speed varies, the only consistent way to measure atmospheric pressure around the world in any weather, is to measure the static pressure of stationary air. This can be done by compensating atmospheric pressure sensors for wind speed or by simply placing them in areas shaded from wind (wind shadows).
Lightning Sensor (Lightning Proximity Sensor)	Electrical and magnetic (electromagnetic) radiation from nearby lightning travels long distances through and around objects, so the placement of lightning sensors quite simple. However, placing them away from industrial electrical sources, electrical lines, industrial machines, fans, electrical motors and wall outlets is critical to minimize measurement noise and false signals.	Lightning radiates energy in many forms. Its light can be seen, and heat can be heard as thunder caused by superheated ionized air expanding into a thunderclap. What we cannot see with our eyes are emitted ultraviolet, infrared, electrical, and radio waves. Electrical and electromagnetic radio waves are the signals that lightning sensors record. Electromagnetic waves from close lightning strikes can damage unprotected sensors and household electronics. These waves travel almost at the speed of light. Industrial equipment, fans, and motors can, however, give false lightning strike signal data from their sparks and EMI; thus, the placement of lightning sensors near these interference sources is not recommended.

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