One Dutch police officer had a very good eye. He immediately noticed a suspicious building, which was only partially covered with snow. This gave him a reason to suspect, which turned out to be true, because the melting of snow from a part of the roof was caused by lamps used in the process of growing marijuana plants!
Snow on all the houses formed a uniform layer with the exception of this one. It couldn’t be a coincidence! It turned out that the building was truly used to grow marijuana on a large scale. Marijuana plants need a large amount of light and an optimum temperature to grow well, which is why the criminals decided to expose the plants to more light. The lamps produced so much heat that it broke through the thermal insulation of the roof and began to melt snow.
Although it is legal to possess small amounts of marijuana in the Netherlands, what police discovered there was no small crop. After the discovery of the illicit activity, the officers were given instructions to watch for similar anomalies in other regions.
Police around the world have different methods for checking the source of suspicious “high-heat” homes. Sometimes, they even use infrared cameras mounted on helicopters, however they aren’t one hundred percent useful in all situations! In 2011, British police raided a house where they thought was a room full of marijuana. It turned out on the spot, however, that the huge source of heat was coming from a big radiator keeping two guinea pigs warm :).