What Are the Recommended Values for Achieving a Cross-Country Flight in Paragliding or Paramotoring?

To plan a cross-country flight in paragliding or paramotoring, the following parameters are essential. Here are the recommended values for each of these parameters, along with explanations of their importance:

1. Top of the Convective Layer (AMSL)

• Definition: Maximum altitude reached by thermal updrafts.

• Recommended Value:

  • 1,500 to 3,000 meters AMSL (Above Mean Sea Level) for optimal conditions.

  • The higher the top, the greater the potential for gaining altitude and distance.

• Note: Beyond 3,000 meters, the air can become too cold, and updrafts too strong, making the flight uncomfortable or dangerous.

2. Cumulus Base Altitude (AMSL)

• Definition: Altitude at which cumulus clouds form, marking the base of thermal updrafts.

• Recommended Value:

  • 1,200 to 2,500 meters AMSL.

  • A higher base allows for flying at greater altitudes and planning longer transitions.

• Note: A base that is too low (less than 1,000 meters) can limit flight options and increase the risk of collision with terrain.

3. Air Temperature at Different Altitudes

• Definition: Air temperature at various altitudes.

• Recommended Value:

  • Gradient of -6.5°C per 1,000 meters (dry adiabatic lapse rate) in the convective layer.

  • A significant temperature difference between the ground and altitude promotes strong thermals.

• Example:

  • Ground: 25°C.

  • 1,000 meters: 18.5°C.

  • 2,000 meters: 12°C.

4. Dew Point

• Definition: Temperature at which air must be cooled to reach saturation (cloud formation).

• Recommended Value:

  • Difference of 5 to 10°C between air temperature and dew point at ground level.

  • A difference that is too small (less than 5°C) can lead to excessive cloud cover, while a difference that is too large (more than 15°C) can limit cumulus formation.

• Example:

  • Ground temperature: 25°C.

  • Dew point: 15°C.

5. Average Thermal Updraft Speed (W*)

• Definition: Average vertical speed of thermal updrafts.

• Recommended Value:

  • 2 to 5 m/s for optimal conditions.

  • Thermals that are too weak (less than 1 m/s) make flying difficult, while thermals that are too strong (more than 6 m/s) can be dangerous.

• Note: Thermal speed depends on the temperature gradient and sunlight.

6. Temperature Gradient in the Convective Layer

• Definition: Variation in temperature with altitude in the convective layer.

• Recommended Value:

  • Greater than the dry adiabatic lapse rate (-6.5°C/1,000 m) to promote strong thermal updrafts.

  • A gradient of -8 to -10°C/1,000 m is ideal for powerful thermals.

• Example:

  • Ground: 25°C.

  • 1,000 meters: 17°C (gradient of -8°C/1,000 m).

7. Turbulence

• Definition: Chaotic air movements that can make the flight uncomfortable or dangerous.

• Recommended Value:

  • None or low for optimal conditions.

  • Moderate to strong turbulence can make flying difficult and increase the risk of accidents.

8. Sea Level Pressure (QNH)

• Definition: Atmospheric pressure adjusted to sea level.

• Recommended Value:

  • 1,013 hPa (standard conditions).

  • High pressure (above 1,020 hPa) is generally associated with stable and sunny weather.

  • Low pressure (below 1,000 hPa) may indicate unstable or stormy weather.

9. Surface Solar Flux

• Definition: Amount of solar energy reaching the ground.

• Recommended Value:

  • 600 to 900 W/m² for optimal conditions.

  • High solar flux promotes ground heating and thermal formation.

• Note: Values depend on sunlight, season, and latitude.

10. Flattened Terrain Used by the Model

• Definition: Simplified representation of terrain in weather models.

• Recommended Value:

  • Moderate to high terrain to promote dynamic updrafts.

  • Windward slopes and wide valleys are ideal for cross-country flights.

• Example:

  • Hills with altitudes of 500 to 1,500 meters.

  • South or southwest-facing slopes in the northern hemisphere.

Conclusion

For optimal cross-country paragliding conditions, the recommended values are:

• Top of the convective layer: 1,500 to 3,000 meters AMSL.

• Cumulus base: 1,200 to 2,500 meters AMSL.

• Air temperature: Gradient of -6.5 to -10°C/1,000 m.

• Dew point: Difference of 5 to 10°C from ground temperature.

• Thermal speed: 2 to 5 m/s.

• Turbulence: None or low.

• Sea level pressure (QNH): ~1,013 hPa.

• Solar flux: 600 to 900 W/m².

• Terrain: Moderate to high, with windward slopes.

These values are general guidelines and should be adjusted based on local conditions and specific weather forecasts. Always consult reliable sources (such as aeronautical weather bulletins) before taking off.

Also see: https://club.mosailes.com/fr/blog/un-pilote-de-parapente-atterrit-dans-leur-jardin--n356