Why does lava cool quickly above ground

Lava cools more rapidly above ground than it does underground because it's much colder above ground than it is underground, speeding up the process.
Think about it this way: If you put a cup of water in two freezers, and Freezer A had a lower temperature than Freezer B, the water in Freezer A would freeze quicker because it is in a colder environment. Hope this helps!

Answerstratovolcanoes///near or in the ring of fire;