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.
From the Marshall Plan to the Truman Doctrine to the Point Four program, Foreign Aid and the Legacy of Harry S. Through what became known as the Truman Doctrine, the president articulated his belief that America had just fought a world war to stop a murderous dictator, and would not then allow the spread of another tyranny.