Hmmm, I didn't think it had anything to do with wet or dry. It was whether the race was stopped due to a hazardous condition as to whether it would invoke "aggregate time".
Found this in the rulebook, note the highlighted text:
1.26.1 Race interruptions
If the Race Director decides to interrupt the race for changes in the weather
or any other reason, red flags
will be shown at the finishing line and at all flag marshal posts, and the Race Director will also switch on the
red lights aroound the track. When they see this, riders must immediately slow down and return either to the
pits or to the starting grid as instructed by the Race Direction. The placings for this part of the race will be
those held at the end of the lap prior to the one in which the race leader and all non-lapped riders
completed a full lap before the red flags were displayed. The following example clarifies this rule.
Example of a 30 lap race race If the red flag is raised when the race leader has completed nine laps and is
on his tenth lap, but not all of the other non-lapped riders have completed their ninth laps, the placings will
be those held at the end of the eighth lap and the restarted race will have to complete 22 laps. If the red flag
is raised when the race leader and all non-lapped riders have completed nine laps and are on their tenth
lap, the placings will be those held at the end of the ninth lap and the restarted race will have to complete
21 laps.
Exception: if the race is interrupted after the chequered flag has been waved, the following procedure is
applied:
1) All riders who have passed the chequered flag before the race is interrupted maintain their placings in the
last lap of the race.
2) Riders who have not passed the chequered flag when the race is suspended are assigned the positions
they held at the end of the penultimate lap of the race.
3) Final placings are calculated by combining the placings of both halves of the race, on the basis of laps
completed and race times.If the race leader and non-lapped riders have not yet completed three whole laps, the race is declared
invalid and is restarted from the beginning. If it proves impossible to restart the race, the event is cancelled
and will not count towards the world championship (article 1.26.2). If riders have completed at least three
laps but less than two thirds of the total distance, the race is restarted whenever possible. If it proves
impossible to restart the race, only half of the points available from that race are assigned (article 1.26.3).
If all non-lapped riders have completed at least two thirds of the total distance, full points are awarded as if
the race had been completed (article 1.26.4).
1.27 Restarting an interrupted race
If a race is to be restarted, as soon as the riders return to the pits or to the starting grid, the Race Director
annnounces what delay there will be before the race start procedure can be repeated. This delay must be
no more than 10 minutes from the appearance of the red flags if the riders return to the starting grid, and no
more than 20 minutes if they return to the pits, conditions permitting.
The placings assigned at the end of the first part of the interrupted race must be communicated to the
teams before the second part of the race begins. If riders have returned to the pits, the re-start procedure
will be identical to a normal start procedure, complete with a sighting lap, etc.. If the riders are already in
place on the starting grid, the re-start procedure begins from the point when the board notifying riders of 5
minutes to go to the start of the sighting lap is displayed.
Conditions necessary for a restart:
Riders in the pit lane
A) If fewer than three laps were completed before the race was interrupted, all riders may re-start, and bikes
may be repaired, changed or even refuelled. The race re-starts with the original starting grid order and runs
for its full number of laps.
B) If more than three laps have been completed, only those riders who were classified in the first part of the
race may re-start. The number of laps in the second part of the race will be that required to complete the
total distance. Bikes may be repaired, changed or refuelled. The order on the starting grid will be
determined according to the placings of the first part of the race. Final race placings will be calculated on
the basis of total race times from both parts of the race.
Riders on the grid
A) If fewer than three laps were completed before the race was interrupted, all riders may re-start, and bikes
may be repaired or changed but not refuelled. The number of laps in the second part of the race will be the
total number of laps minus two or three, as announced by the Race Direction. The original starting grid
order is maintained.
B) If more than three laps have been completed, only those riders who were classified in the first part of the
race may re-start. Bikes may be repaired, changed but not refuelled. The number of laps in the second part
of the race will be that requred to complete the total distance, minus two or three, as announced by the
Race Direction. The order on the starting grid will be determined according to the placings of the first part of
the race. Final race placings will be calculated from the total race times from both parts of the race.
