You are landing on a Caribbean island (hot and dump) after a long flight at FL410 with your 604, for a short stop to refuel.
During the refueling/short walkaround you notice frost on the lower part of your wings formed by cold soaked fuel.
Can you disreagard it and takeoff?
Wait for an hour or two watching the frost to dissipate?
Challenger 604 AFM, as at Rev 66, Feb 01/07 (and subs), Operating Limitations, page 02-04-2:
WARNING
Even small amounts of frost, ice, snow or slush on the wing leading edges and forward upper wing surface may adversely change the stall speeds, stall characteristics and the protection provided by the stall protection system, which may result in loss of control on take-off.
NOTE
1. Comprehensive procedures for operating in cold weather are provided in the Operating Manual, Volume 1, Chapter 6; SUPPLEMENTARY PROCEDURES – COLD WEATHER OPERATION .
2. Take-off is permitted with frost adhering to the underside of the wing that is caused by cold soaked fuel, in accordance with the instructions provided in the Operating Manual, Volume 1, Chapter 6; SUPPLEMENTARY PROCEDURES – COLD WEATHER OPERATION – PRE-FLIGHT PREPARATION – External Safety Inspection .
So, follow those noted instructions, and you can go. Otherwise, either wait or de-ice.