It's been a week of snow, ice and frost for many parts of the UK this week, especially up in the north of England and Scotland.

       As much as a foot of snow fell on Sunday in areas of Leeds, as well as further north in Newcastle, Scotland and in Wales.

       And in the days that followed, temperatures dropping as low as -16C overnight and rising to just -1C in the daytime left many households facing snow which was frozen in place on driveways, on roads and on the top of their houses' roofs too.

       But if you're feeling eagle-eyed you might notice a telltale sign that the police use to spot houses which could have occupants up to no good during the snow.

       READ MORE: Drivers in England urged to put blankets on car until Monday

       Kingsbridge Police famously shared this image of a house taken in Amsterdam during a freezing, snowy day with a dead giveaway about some wrongdoing inside.

       The police issued the image to warn others about growing drugs, and how the snowy conditions make it very easy for officers to spot.

       During cannabis production, hot lights and heaters are used to encourage plants to grow. Photos inside cannabis farms often show rows of the illegal drug under heaters.

       Police helicopters can employ thermal imaging cameras to see the heat signature of roofs all year round, which can often be a giveaway, but such high tech is not needed in the snow.

       This picture was taken by officers in Haarlem near Amsterdam, and was shared on social media by Kingsbridge police, who said: "If we are lucky enough to have some decent snow over the next few days, and if anybody notices a sight like this, can you let us know."

       Offices in Holland uncovered a city centre cannabis farm after spotting the highly suspect lack of snow on the roof of one property, while neighbouring buildings suffered a heavy blanketing.

       Officers raided the home after spotting its snow-free roof, and released the picture after they discovered a cannabis farm inside, with plants growing under heat lamps, hence the melting snow.

       Police in the UK have been known to use their helicopter patrols to look out for similar suspiciously roofs.