0
$\begingroup$

Recently, India's prime minister Narendra Modi commented on how cloudy weather can help a fighter jet escape from radar. Is there any technical reasoning to back these comments?

Here is the quote in question:

In the interview by TV channel News Nation on Saturday, PM Modi said, "The weather suddenly turned bad, there were clouds... heavy rain. There was a doubt about whether we can go in the clouds. During a review (of the Balakot plan), by and large the opinion of experts was - what if we change the date. I had two issues in mind. One was secrecy... second, I said I am not someone who knows the science. I said there is so much cloud and rain. There is a benefit. I have a raw wisdom, the clouds can benefit us too. We can escape the radar. Everyone was confused. Ultimately I said there are clouds... let's proceed."

https://www.ndtv.com/india-news/controversy-over-pm-narendra-modis-cloud-can-help-us-escape-radar-comment-on-balakot-air-strikes-2036402

$\endgroup$
  • 3
    $\begingroup$ To be completely fair, that sounds like a traditional politician's way of appealing to his popular base by reinforcing his image as both a great leader whose plans are not immediately obvious ("The Lord works in mysterious ways...") and by giving the less educated voters something to feel good about ("I do not know the science but I succeeded while the know-it-alls with degrees and stuff were confused"). A rather textbook approach. $\endgroup$ – AEhere supports Monica May 15 at 13:37
  • 1
    $\begingroup$ I can interpret it as (big?) stormy clouds, not only cloudy weather. What makes me wonder is: jets normally flight above those, so for who he is trying to hide $\endgroup$ – jean May 15 at 14:47
3
$\begingroup$

Radar relies on electromagnetic wave propagation: from a source, to the target and back to a receiver.

Anything that alters the behavior of these waves along the way will impact the performance of the radar station. For example:

  • A target hiding behind terrain will be harder (but not necessarily impossible) to detect, because the terrain will absorb the outgoing emissions before they even reach the target.
  • If the target is in plain sight but shaped in such a way that all the incoming radar energy is reflected in a direction different from that of the receiver, then it will not be detected (this is the method employed on the F-117).
  • If the target is in plain sight but the return signal comes back accompanied by a lot of duplicates purposefully emitted by the target, it will complicate the task of figuring out which is the correct reflection, delaying or preventing a valid solution.
  • If the target is coated in a material that absorbs all the incoming energy, the radar station will never see a return, and thus think there is nothing there to detect (another technique used by Low Observability aircraft). This one is relevant to your question!

The media between the emitter and the target needs to allow the waves to travel, and while the best media is vacuum, air is not terrible either. At least normal, ISA air, things get complicated in the high atmosphere, or at high temperatures, or when electromagnetic fields (caused by thunderstorms, the Earth's core, etc.) come into play.

In the case of water suspended in the atmosphere, it can absorb the radar emissions and thus limit their effective range. However, it does so mostly at certain wavelengths, which are the ones at which water molecules can best capture incoming energy. One such wavelength is the one used in microwave ovens, because food tends to contain water, and heating the water is a fast way of heating the food.

So the ultimate answer to your question is, there is some kernel of truth in those statements, but how large it is is very debatable. Some radars, particularly modern high-frequency ones, operating in the millimetre band, will see noticeable losses due to coulds. Other radars, particularly those in the low GHz range or lower, will fare considerably better, although the lower frequencies have their own disadvantages in terms of resolution and antenna size requirements. Ultimately, defense organizations are quite aware of their equipment's capabilities and usually take steps to mitigate any drawbacks, so it is unlikely that some cloud cover will substantially impair a modern IAD network.

$\endgroup$
0
$\begingroup$

Modi is correct. Adverse weather can affect the quality of the return signal from a radar, and in some cases can mask the objects someone is trying to identify. A good example of this is the Air France flight 447 accident. One of the theories as to why the pilots chose to fly into severe weather is that the area of severity was masked by other weather ahead of it on the flight route, and once they realized what they were flying into it was too late to try to fly around it.

$\endgroup$
  • $\begingroup$ Is this the same case for ground based radar trying to detect flying aircrafts and clouds can mask it? $\endgroup$ – Talk is Cheap Show me Code May 15 at 12:02
  • 3
    $\begingroup$ That theory about the weather radar seems absent from the final report, which does however state: "But the aeroplane had not encountered, before or during the accident, an exceptional meteorological situation from the point of view of phenomena that are traditionally avoided in stormy environments" and "The recording of the load factor showed that the turbulence remained light.". Weather is also not listed as a causing or contributing factor for that accident. $\endgroup$ – AEhere supports Monica May 15 at 12:23
  • 1
    $\begingroup$ Final reports by definition are not supposed to contain theories. I would suggest this as interesting factual material about the weather that confronted AF447... weathergraphics.com/tim/af447 $\endgroup$ – Juan Jimenez May 16 at 8:58
  • 2
    $\begingroup$ @HungryforChallange Radar and clouds don't really care where the signal is coming from. $\endgroup$ – Juan Jimenez May 16 at 8:58
  • $\begingroup$ @JuanJimenez It's a nice analysis, and indeed it was correct in theorizing that icing may have started an issue that cascaded into the crash, but the theory about the radar masking it pure speculation and not held up by the final report, so I question the value of repeating it. The final report does address the case of the weather radar being in calibrated mode and that the captain may have been more concerned if he had adjusted the gain, but at no point is masking considered an issue. $\endgroup$ – AEhere supports Monica May 16 at 11:52

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.