If warm air rises because it is less dense than cold air, then why does the air get colder with height in the

Question: If warm air rises because it is less dense than cold air, then why does the air get colder with height in the troposphere (the closest layer of the Earth's atmosphere)? In other words, why doesn't the warm air near the surface continuously rise, and the cold air aloft continuously sink, replacing it.
- Keywords:
  atmosphere,
  cold,
  height,
  rises,
  warm air
Asked by caseym to Ed, Katie, Sam, Steve, Vera on 19 Jun 2011.
- Ed Morrison answered on 17 Jun 2011:
  
  Air gets colder as you rise because it is further from the earth. Heat energy comes from the sun and warms the earth, and the earth then radiates this heat outwards (upwards to us), a bit like a radiator. The further away from the radiator you are (the higher up), the colder it feels.
  
  Warm air near the earth’s surface does rise, but as it does so it cools down and becomes denser. Likewise cold air will sink, but as it does so it warms and becomes less dense. Ultimately you get a general pattern of warm air at sea level and colder air above. Does that make sense?
- Steven Daly answered on 17 Jun 2011:
  
  Good question. The answer is that the higher you go in the atmosphere, you get less and less air left, which makes it colder. Heat is actually related to two properties of the molecules in the air: how many there are and how fast they are going, and the heat we feel from the atmosphere is related to how many are hitting us. As you go far out into the atmosphere there is less air and so it is colder.
- Sam Tazzyman answered on 17 Jun 2011:
  
  The constant cycling of warm air rising, then cooling, then sinking is called a “convection cycle” if I remember correctly from school, and even happens in smaller spaces like rooms in a house.
- Vera Weisbecker answered on 17 Jun 2011:
  
  Wow, you guys really know your stuff!
- Katie Marriott answered on 19 Jun 2011:
  
  I agree with Steven! Temperature and Pressure are connected. the further up you go the less air there is and so the pressure decreases which would cause a decrease in temperature. The formation of clouds also causes cooling of the air.