Why is Tibet so cold?
As the summer has been arriving fast here in Europe, I was curious enough to look at a temperature map of the world. The closest to the equator you go, it gets hotter, or so I thought.
What stood out as a cool patch all year long was the area around Tibet. Why is it so cold, despite being so close to the earths equator?
Tibet is a vast region located on the Tibetan Plateau, which is also known as the “roof of the world”. It spans an area that goes beyond the political boundaries of China, and includes parts of India, Nepal, Bhutan and Myanmar. Tibet has a fairly uniform climate: freezing and windy but dry in winter and mild to cool in summer, with considerable variations between night and day due to the strong solar radiation that is typical of high altitudes.
But the temperature of Tibet in different seasons is not only decided by the season as the altitude of Tibet varies greatly from a minimum altitude of around 3600m to 5000m at some passes. The wind at Everest Base Camp can be very cold. At altitudes higher than Lhasa the nighttime temperatures will invariably be below zero centigrade. The north is a bit colder than the south, but the temperature varies mainly with altitude; the only significant difference between the areas is that the eastern part is affected by the summer monsoon, so it receives a bit of rainfall (sometimes even abundant) in summer.
The average annual temperature of Tibet is about 7°C (44.6°F), but it can range from -15°C (5°F) in winter to 30°C (86°F) in summer. The coldest month is January, with an average temperature of 0.3°C (32.6°F) in Lhasa, the capital city. The hottest month is June, with an average temperature of 17°C (62.7°F) in Lhasa. However, these are just averages, and the actual temperature can vary a lot depending on the location and time of day. For example, in Lhasa, winter nights are freezing cold, but it almost always exceeds freezing (0°C or 32°F) during the day. In summer, Lhasa is mild, quite cold at night, about 10.5/11 °C (51/52 °F), and pleasantly warm during the day: the average is 23.5 °C (74 °F) in June.
So why is Tibet so cold despite being close to the equator? The main reason is the high altitude. Tibet is located on a plateau that has an average elevation of about 4500m (14760ft) above sea level. This means that the air pressure is lower than at sea level, and the air contains less oxygen and water vapor. As a result, the air can’t hold as much heat as at lower altitudes, and it cools down faster when it rises or expands. This also affects the boiling point of water: water boils at lower temperatures at high altitudes than at sea level. For example, water boils at 90 °C at 3,000 meters (195 °F at 9,800 feet), at 87 °C at 4,000 meters (189 °F at 13,100 feet), and at 84 °C at 5,000 meters (183 °F at 16,400 feet).
Another factor that influences the temperature of Tibet is the distance from the sea. Tibet is surrounded by mountains that block the influence of warm and moist air masses from the Indian Ocean and the Pacific Ocean. This makes Tibet a landlocked region with a continental climate that has low precipitation and high evaporation. The lack of moisture also reduces the greenhouse effect that traps heat in the atmosphere. Therefore, Tibet has low humidity and clear skies for most of the year, which allows more solar radiation to reach the ground during the day but also more heat to escape into space at night.
In conclusion, Tibet has a unique climate that is characterized by low temperatures, high altitude, low precipitation and high solar radiation. It is one of the coldest regions in China and in the world. If you plan to visit Tibet, you should be prepared for extreme weather conditions and altitude sickness. You should also respect the local culture and environment that have been shaped by this harsh climate for thousands of years.
