On a clear night, there is nothing to stop heat radiating from the ground out to space. You may notice that frost will form even though a thermometer on a wall shows a temperature of 33 or 34F. That is because the ground can get colder than the air above it, by radiating heat to space.
From Wikipedia, the free encyclopedia. The Truman Doctrine was an American foreign policy to stop Soviet imperialism during the Cold War. It was announced to Congress by President Harry S. Truman on March 12, 1947 when he pledged to contain Soviet threats to Greece and Turkey. No American military force was involved; instead Congress appropriated a free gift of financial aid to support the economies and the militaries of Greece and Turkey.
Summary. 1  The Truman Doctrine grew out of George Kennans 1946 long telegram which argued that the US should follow a policy of containment to stop Russian expansion. Then, in February 1947, the British announced that they were withdrawing their soldiers from Greece.