The Alkmaar Pieter Bliek ‘hunts’ for frost in various dune pans along the North Holland coast. He has several weather stations there for research, which accurately indicate how hot or cold it is to the second. “Of course we are going for a record”, says a cheerful Bliek, who was still at the beginning of this month a temperature of -1.7 degrees measured at the Winnummer Duinen.
Together with the Belgian frost fighter Karel Holvoet, the Alkmaarder – who found out that the coldest dune pan of the Netherlands in the dunes of Schoorl – scientific research into ‘temperature development in dune pans’. “There has never been thorough research into this,” says Bliek.
And that while it can tell a lot about, for example, the planting: “When the weather is calm in the summer or in early or late summer, it can be very frosty,” says the frost fighter. “It can sometimes be even colder in the dunes than in the east of the country, and that has an effect on the plants.”
For example, last summer he was in a dune pan in the Kennemerduinen, where it was freezing 4 to 5 degrees Celsius. “Leaves had already turned brown below the frost line, while those a few meters higher were still completely green,” says an enthusiastic Bliek.
heavy air
The fact that it can freeze in the summer is a normal phenomenon, says de Alkmaarder. “Cold air is heavy and it sinks to the lowest point in dune pans. In calm, clear weather, that air can become very cold, sometimes ten to fifteen degrees colder than in the area.”
As far as Bliek knows, however, no frost has ever been recorded in the Netherlands between 20 July and 21 August. “The coldest recorded temperature at 1.5 meters is 1.6 degrees and the lowest, at 10 centimeters, exactly 0.0 degrees Celsius.” He hopes to change that: “Last summer in Camperduin I measured 0.1 degrees, so we are going for a record.”
Bliek previously explained to reporter Tom Jurriaans how to become a frost fighter: