- The ground radiates solar energy into air
- Solar energy can warm up the air
- Therefore, the solar energy radiated by the ground can warm up air

- If gas is heated then that gas will rise
- Air is a kind of gas
- Therefore, if air is heated then air will rise

- The solar energy radiated by the ground can warm up air
- If air is heated then air will rise
- Hence, the solar energy radiated by the ground can cause the air to rise

- The solar energy radiated by the ground can cause the air to rise
- Travelling up a mountain side is a kind of rising
- Therefore, the solar energy radiated by the ground can cause the air to travel up a mountain side

So, the solar energy radiated by the ground can cause the air to travel up a mountain side
Q: An air mass in a valley travels up a mountainside. What causes the movement of this air?
Context:
- If gas is heated then that gas will rise 
- The ground radiates solar energy into air 
- Travelling up a mountain side is a kind of rising 
- Air is a kind of gas 
- Solar energy can warm up the air