It needs that extra heat applied to it.

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Added to that eye-widening pub fact is that the heat insulation applied liberally to the engine bay and underside is a substance called 'Aerogel' - a compound formulated by NASA to insulate the Mars Rover.

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For it means that heat does not have to be applied to allow them to grow: or even if it does, less heat than would be necessary further north.

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With cleaner heat sources came cleaner flavor, and smoke became something applied at will.

WSJ: Smoky Desserts: Smoke Signals