Lecture Notes: Fronts in Aviation

Introduction to Fronts

• A front is a boundary layer between two types of air masses.
• Importance for pilots: Approaching fronts indicate a change in weather.

Types of Fronts

1. Warm Fronts

   • Warm air mass advances, replacing cold air.
   • Moves slowly (10-15 mph).
   • Characteristics:
     • High humidity.
     • Stratiform and cirri clouds; potential for fog.
     • In summer, can trigger cumulonimbus clouds.
     • Light to moderate precipitation.
     • Poor visibility during passage; improves after.
     • Barometric pressure slightly rises, then decreases post-passage.

2. Cold Fronts

   • Colder air forces warmer air upwards.
   • Moves faster (25-30 mph, up to 60 mph recorded).
   • Characteristics:
     • Cloud variation depends on warm air mass stability.
     • Cloud types: Towering cumulus, cirrus, possibly cumulonimbus.
     • Possible lightning, thunder, hail, tornadoes with strong cold fronts.
     • Squall lines: Intense thunderstorms ahead of cold front; avoid when flying.
     • Weather clears rapidly post-passage.

3. Stationary Fronts

   • Occurs when two air masses are of equal force.
   • Can linger over an area for extended periods.
   • Mix of weather conditions from both warm and cold fronts.

4. Occluded Fronts

   • Fast-moving cold front catches up to a slower warm front.
   • Two types:
     • Cold Front Occlusion: Colder cold front air replaces warmer air; mixed weather.
     • Warm Front Occlusion: Warm front's cold air is colder than cold front's air; more severe weather with embedded thunderstorms, rain, and fog.

Comparison: Warm vs Cold Fronts

• Warm Fronts:
  • Slow movement.
  • Low ceilings, poor visibility, some rain.
  • Less intense.
• Cold Fronts:
  • Fast approach, little warning.
  • Rapid weather changes.
  • More intense weather.

Conclusion

• Fronts are crucial for understanding weather changes in aviation.
• Next topic: High and low pressure systems.