Climate change reshapes gliding season in the Netherlands: more sun, but new risks
Dutch gliding enthusiasts face a mixed outlook as climate change alters weather patterns. While sunnier summers may boost thermals, fewer clouds and sudden storms could disrupt flights, impacting this sustainable sport’s future.
| Key Data | Details |
|---|---|
| Gliding Season | March–October (winter: maintenance) |
| Thermal Dependence | Rising air bubbles (thermals) enable engine-free flights |
| Climate Impact on Thermals | More sunshine and drier soils may strengthen thermals |
| Cloud Formation | Fewer cumulus clouds expected, making thermals harder to locate |
| Storm Risks | Increased likelihood of heavy showers, hail, and downbursts (e.g., Leersum 2021) |
| KNMI Scenarios | Climate dashboard tracks changes: drier summers, intense rainfall |
| Glide Ratio | Modern gliders: 1:60 (60 km distance per 1 km altitude loss) |
The Royal Netherlands Meteorological Institute (KNMI) monitors climate trends and provides data-driven insights to inform sectors like aviation. This report highlights how shifting weather patterns may affect recreational gliding, a niche but weather-dependent sport in the Netherlands.
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Read the full translated article below
Gliding in the Netherlands in a Changing Climate
The gliding season has begun again. Gliding is a sport that is highly dependent on the weather. Thermals—rising air bubbles created by the warming of the Earth's surface—enable long-distance flights without an engine. Due to climate change, temperature, sunshine, drought, and rainfall patterns in the Netherlands are shifting. What does this mean for gliding?
What is gliding?
Gliding involves flying without an engine. In the Netherlands, gliders are typically launched using a winch or towed aloft by a powered aircraft. Some modern gliders are equipped with a small deployable propeller to take off independently or to ensure a safe landing.
Once airborne, gliding revolves around finding thermals (image 1). Thermals consist of bubbles or columns of rising air in which a glider can climb by circling. These are most common during the summer half of the year, when the Earth's surface heats up significantly due to solar radiation while the air above remains relatively cool. Conditions after the passage of a cold front are therefore often ideal for thermals.
In mountainous regions, altitude can also be gained by rising air along mountain slopes or through so-called lee waves behind mountain ranges. In the Netherlands, however, gliders are almost entirely dependent on thermals. Under favorable conditions, flights of 500 to 1,000 kilometers are regularly made from the Netherlands—a particularly sustainable form of aviation.
When there is no thermal lift and no horizontal wind, little of note happens: a glider slowly descends. In calm air, the sink rate is approximately 0.5 to 1 m/s. Modern gliders have a glide ratio of about 1:60, meaning that with a loss of one kilometer in altitude, roughly sixty kilometers can be covered.
The Dutch gliding season typically runs from March through October. In winter, the likelihood of thermals is low, and gliders undergo maintenance.
How is the climate in the Netherlands changing?
The climate is changing. Average temperatures are rising, evaporation is increasing, and the atmosphere is becoming more humid. Periods of extreme heat are also expected to occur more frequently.
For the Netherlands, it is also expected that:
- summers will generally be drier and sunnier
- heavy rainfall will occur more often and may be more intense
- precipitation will more frequently fall in short bursts
- wind gusts and downbursts during showers may increase
However, little change is expected in average wind speed and wind direction. The Royal Netherlands Meteorological Institute (KNMI) has developed various climate scenarios based on future greenhouse gas emissions. These changes can be viewed in graphs on the climate dashboard.
More sunshine and dry soils: opportunities for thermals
At first glance, a warmer climate seems beneficial for thermals. However, the relationship is complex, as thermals depend not only on temperature but also on moisture and the vertical structure of the atmosphere.
For the summer, there appears to be cautiously good news for gliders. More sunshine is expected on average. This increases the temperature difference between the ground and the air above, which can strengthen thermals.
Additionally, dry soil heats up more quickly because less energy is required to evaporate soil moisture. This can further stimulate the development of thermals.
A drawback is that thermals will more often be "dry." With less moisture, cumulus clouds (fair-weather clouds) will form less frequently. Gliders use these clouds as indicators of where thermals are located.
The ideal scenario for many gliders is a line of cumulus clouds—a so-called cloud street—aligned with the flight path. Beneath the clouds lies rising air, allowing a glider to fly for kilometers without losing altitude. Such a situation occurred last Sunday (image 2). In drier conditions, this will happen less often.
Heavier showers and downbursts
In terms of wind and turbulence during takeoff and landing, the climate appears to change little. Since average wind speed and direction are not expected to change significantly, the risk of strong crosswinds likely will not increase.
The situation is different for days with heavy showers (image 3). In a warmer and more humid atmosphere, a great deal of water vapor can condense during showers. This releases heat, causing the upper air to warm more than the air near the surface. This can reduce the overall instability of the atmosphere and, consequently, the strength of thermals.
In practice, this effect is often less relevant for gliders, as flying is typically avoided during heavy showers.
However, the likelihood increases that on an otherwise good flying day, a sudden heavy shower may develop, accompanied by hail and strong wind gusts. A particularly notable type of shower is the pulse storm.
These storms form under the following conditions:
- high temperatures
- high humidity in the air
- light winds
- a high cloud base
The storm develops rapidly and often dissipates just as quickly. When precipitation falls from the cloud and evaporates on the way down, the air cools significantly. This can create a powerful downward air current: a downburst or microburst.
If this reaches the ground, the air can spread horizontally with wind gusts exceeding 100 km/h. On June 18, 2021, such a downburst struck Leersum, causing significant damage to homes and snapping thousands of trees like matchsticks.
Conclusion
Climate change presents both opportunities and risks for gliding in the Netherlands. More sunshine and drier soils can promote the development of thermals, which is favorable for long flights. At the same time, cumulus clouds may form less frequently, making thermals harder to locate.
Additionally, the likelihood of heavy showers and localized downbursts is increasing, introducing extra risks during the flying season.
All in all, gliding remains strongly dependent on daily weather conditions. Even in a changing climate, good and poor flying conditions will continue to alternate.
KNMI climate report by Kasper Gerritsen
More information
- All KNMI climate reports
- What do balloon pilots in the Netherlands notice about climate change? (climate report May 2025)
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