Applying carb heat will heat out of the range (in most cases).
Flying our PA28-180 today, fitted with a carb temp gauge, showed -10deg C, near the lower end of the yellow arc. Applying carb heat only raised the temp to the top end of the arc, not out of it. Still, got about a 50RPM drop in revs, followed by the classic return to the original RPM 'no rise, no ice'.
You might have mentioned NOT using carb heat in very cold conditions, when doing so can put the inlet temp INTO the carb ice range, from a nice too-cold position.
We regularly get carb ice in the PA28 when starting from cold over grass, good demo to the student of what it looks like. Personally, I've never seen significant carb ice in a PA28-180, over decades. Now, in my C150, wow, a different story!
I think there are very few days in the UK when the conditions are outside the critical part of the graph.
Next thread - 'Use of Pitot Heat'.
TOO