Science & Technology

How clouds don’t matter when it comes to radar technologies

Recent remarks make one wonder about the efficacy with which important information is ferried to the prime minister, and if he is aware about how the technologies actually work

 
By Akshit Sangomla
Last Updated: Tuesday 14 May 2019
How clouds don’t matter when it comes to radar technologies

None of the radar technologies that track aircrafts and are currently under use are hindered by clouds, which are basically condensed clusters of water vapour in the atmosphere.

With all the scientific and defense machinery of the country at his disposal, the Prime Minister of India should have been aware of this fact. And if he had been aware of this fact he should not have made the careless statement that he had advised worried Indian Air Force (IAF) personnel to carry out the Balakot air strikes despite inclement weather on February 26, 2019 morning. The apparent logic for this advice was that a cloudy sky would prevent radar detection of IAF aircrafts.

Aircraft whether military or civilian can easily be tracked by a host of technologies on the ground and in the air. At first, the aircraft is tracked using primary surveillance radar which sends out electromagnetic signals (mostly radio waves), and then reads and analyses the ones that bounce back objects in its range of operation.

This is done by calculating the time taken by radio waves to traverse the distance from the point of their origin to the object being tracked, and return back to the same location. By doing this, it knows about the approximate location of the object, its basic shape and size.

Though the precision of the data may vary, all radars work on this basic scientific principle. Secondary radar, which is used by air traffic control, receives signals from the aircraft’s onboard transponder which transmits them regularly. These transponders can be of various types, for example the Automatic Dependent Surveillance Broadcast (ADS-B) is used in many commercial aircrafts.

Even if the transponder is switched off, for a top-secret operation like the Balakot airstrike, the primary radar can still pick up airplanes flying by. Apart from these, there are military grade radars which have much higher precision in locating aircrafts even if their transponders are switched off.

As far as radio waves penetrating through clouds goes radio waves have to simply penetrate sparsely dense group of water molecules to achieve this. The fact that radio waves can even penetrate water in much denser formations like lakes and rivers shows that water vapour should not be much of an issue.

They do have a problem in penetrating ocean waters, but that is because of the salt content which prevents efficient transmission. This happens because the radio waves start interacting with the ions that form the salt and become dispersed. This is why detecting submarines is difficult and very different technologies are used for the purpose.

As the clouds do not pose a problem the IAF used advanced electronic warfare equipment on board the Mirage 2000 aircrafts to jam Pakistani radars just before the planes invaded enemy air space to carry out the attacks. The IAF should have briefed the Prime Minister about this, if it did not do so.

The PM, however, went ahead making this remark during a television interview and became a laughing stock for people on Twitter and has been rebuked by radar experts. This makes one wonder about the efficacy with which important information is ferried to the prime minister, and if he is aware about how the technologies actually work.

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