Using infra red for area bombing

I've seen lots of TV programmes about are bombing campaigns during World War II, to sum up, they didn't like bombing in the day time because that made it too easy for enemy fighters, but the problem at night was actually finding the target.

An obvious counter-measure was having a blackout, it's fairly easy to get everybody to turn the lights off, have black out blinds etc. So they invented all manner of radio guidance systems, all of which were then jammed by the other side.

But you cannot just cool down a whole city. According to Wiki, the heat island effect was known about since 1810 and the temperature difference is "several degrees". And according to this, the Germans had been working on infra red scopes for tanks and so on.

So assuming the technology existed, if you had an infra red scope in the lead bomber pointing downwards, he'd be able to find his way across enemy territory in complete darkness by comparing the brighter/warmer smudges against where towns and cities are on a normal map, drop a few incendiaries to get the party started and hey presto.

The other good news about using an infra red scope, compared to radio guidance or radar, is that it doesn't emit anything which the enemy can detect from a distance.
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Which brings me on to another topic.

It was very difficult shooting down an aeroplane using ground based artillery, it is pure guesswork and the calculations are too complicated. But shining a searchlight on an aeroplane is a lot easier. If you can get two searchlights (or even better three searchlights) to lock on to and track an aeroplane, then using triangulation and so on, you can work out where it is and how fast it is moving.

All you'd have to do then is co-ordinate this with the artillery so that they are firing shells exactly where the aeroplane is going to be after however many seconds it will take it to reach that spot.

I was once talking to an old German guy who had to assist the anti-aircraft people in his youth. He told me that he'd asked the same question and the boss of the battery told him to shut the f- up about it, the military were actually doing top secret research into exactly that approach.