Weather radars send directional pulses followed by a waiting time to “listen” to return signals to determin if echos are coming back from precipitations. Only Doppler radars can detect with certainty the presence of small in a cumulonimbus.
These radars have a cost of several million Euros, which use solutions as part of an anti-hail protection?
In order to have a local weather picture, you can buy a low cost weather radar which will allow you to start your anti-hail devices only when there is a high POH (Probability Of Hail).
This weather equipment is an X-band radar system and not a Doppler system, which is why it is the least expensive weather detection equipment on the market. The false alarm rate is higher but detection thresholds can be adjusted in accordance with user expectations and can be calibrated to detect specific meteorological conditions.
There are a lot of companies and websites which propose weather warning services. You can receive messages via cellphone or email for each hail storm report.
These alerts are based on Doppler Weather radar information, very reliable for hail cloud detection but often, alerts are received throughout an entire day which complicate the decision of when to activate the anti-hail devices.
Hail forms in a particular kind of clouds, cumulonimbi:
You can evaluate the risk of hail fall if you observe:
- the shape of clouds (upper part with a shape of anvil)
- cloud thickness (5000m minimum)
- electrical activity inside the cloud (numerous lightnings)
- precipitation level (strong rainfalls)
- color of cloud : hail clouds exhibit a characteristic green coloration
We can evaluate if there is a risk of hail fall with factors based on statistical and empirical data but this approach is limitited and less effective way to protect property because one cannot observe critical points during the night or when one is absent.