- Altitude: As altitude increases, the air becomes less dense and can hold less heat, causing temperatures to drop. On average, the temperature decreases by 6.4 degrees Celsius (3.6 degrees Fahrenheit) for every 1,000 meters (3,280 feet) gained in altitude.
- Reduced atmospheric pressure: The atmospheric pressure is lower at higher altitudes, which allows heat to escape more easily into space, contributing to cooler temperatures.
- Less solar radiation: Mountains often receive less direct solar radiation than lower-lying areas due to cloud cover and shadows cast by peaks and ridges, leading to cooler conditions.
- Air circulation: Valleys and basins in mountainous regions can trap cold air, leading to temperature inversions where colder air settles at the bottom and warmer air rises, resulting in cooler conditions overall.
Warmer in the city
- Urban heat island effect: Cities have a higher concentration of buildings, roads, and other infrastructure that absorb and trap heat, leading to warmer temperatures compared to rural areas. These surfaces release heat slowly, causing the urban environment to feel warmer, especially during nighttime.
- Lack of vegetation: Urban areas often have less vegetation compared to rural areas, and plants play a role in regulating temperature through processes like photosynthesis and transpiration. With fewer plants to provide shade and release moisture into the air, cities tend to be warmer.
- Pollution and aerosols: Urban areas often have higher levels of air pollution, including particulate matter and aerosols, which can trap heat and contribute to warmer temperatures.
- Human activity: Human activities in cities, such as transportation and industrial processes, release heat and energy into the environment, contributing to warmer conditions.
