Dry slopes, sometimes called "plastic slopes," artificial surface slopes, or "dryland skiing" are ski slopes covered with a special material that makes it possible to use regular skis, snowboards, sleds, or other sliding devices on them – all year round, whatever the weather.

The first of these slopes began to appear about 60 years ago as skiing became more and more popular in northern European countries like Great Britain, Belgium, and Holland, but it was difficult for people to reach the ski slopes very easily far away across Europe.

The most successful of those early slopes were covered by a product called Dendix, which still exists today. It is made of a honeycomb of bristles on a giant metal net, like a long upturned scrubbing brush. Skis could turn and the flexing bristles give support, but it can be painful when you fall. Later systems incorporated water sprinklers to make the surface more slippery.

More plastic slopes began to evolve in the 1970s and '80s, which we still made with bristles, but this time plastic ones. These slopes were especially popular in northern European countries like Belgium and Holland. Variations on this theme have been a big hit even in the past two years for summer tubing runs at conventional ski resorts in Europe, Japan, and North America,

The most recent development in artificial surface slopes is the carpet type surface which evolved in the 1990s. One of the best known manufacturer of these is Snowflex. They believe that their material is the closest to real snow, as well as being the most flexible – so that terrain features like pipes and jumps for freestylers can be created – and one of the softest surfaces so least likely to cause injury.

Apart from in special centres with these types of year-round slopes – most of them between 50 and 200m (150 and 650 feet) long – artificial ski surfaces are used in many other places. Ski jumpers lay ceramic tiles on summer ski jumps to slide over at speed and conventional ski areas may put small squares of artificial slope surface on chairlift loading and unloading areas, for example, to keep them "slidey" if the snow gets worn away.

Yet another variant are big indoor machines that are revolving carpet versions that work like runners treadmills for skiers – these are very popular in Holland, where are about 30 of them are operational.

Today there are more than 500 dry slopes currently operating in 40 countries and six continents worldwide. Here were more than 100 slopes across Great Britain at their peak in the 1970s. That figure is nearer to 75 today.

Some of the biggest centres include Sheffield, in Yorkshire, where the total length of slopes is 1.5km (one mile) and a small piste map is needed to find your way around.

The slopes at Wycombe Summit, north of London add up to over 700m and they plan to open an additional indoor snow centre there next year. Edinburgh’s Midlothian ski centre is one of the few artificially surface slopes to be accessed by a chairlift rather than a surface tow, and has a 750m slope with a 100m vertical.

Although now superseded to some extent by some of the indoor snow centres (which offer real snow training, but milder slopes), Midlothian, once called Hillend, has for many years been the training base of many British racers.

They are also the place where hundreds of thousands of people new to the snow sports try strapping on boots and clicking on skis or boards for the first time and learn the rudiments of the skiing or boarding before travelling out to the snow resorts of Europe or North America with some invaluable grounding in the "real thing."

Read Paul Doherty's A Map To the World's Indoor, Dry Ski Slopes for more information on dry ski slopes, details on indoor ski slopes, and links to relevant stories.