FAA Instrument Rating Airplane (IRA)Weather and Weather ServicesEasy
A pilot receives a surface report of ice pellets (PL) at their destination. What does this observation most strongly suggest about conditions aloft?
- AThe freezing level is at the surface and temperatures increase with altitude
- BA layer of air warmer than freezing exists aloft, with a subfreezing layer near the surface
- CThe entire atmospheric column from the surface to cloud tops is below freezing
- DConvective activity is occurring with strong vertical development
Show answer & explanationAnswer & explanation
Correct answer: B. A layer of air warmer than freezing exists aloft, with a subfreezing layer near the surface
Ice pellets form when snow melts in a warm layer aloft, then refreezes into ice pellets as it falls through a subfreezing layer near the surface. This is a strong indicator of a temperature inversion and the potential for freezing rain nearby, since the same warm layer could produce freezing rain if the surface cold layer is shallower.
Why the other options are wrong
- A. If the freezing level were at the surface, precipitation would fall as rain, not refreeze.
- C. If the entire column were below freezing, precipitation would fall as snow, not ice pellets.
- D. Ice pellets are associated with stratiform winter precipitation, not convective activity.
Ice Pellets (Sleet)
Frozen precipitation formed when snow melts in a warm layer aloft and refreezes falling through a subfreezing layer near the surface.
- Indicates a warm layer aloft above a subfreezing surface layer
- Often signals nearby freezing rain conditions
- Reported as PL in METAR
Memory trick: Sleet bounces because it froze twice: melt then freeze.