London is significantly influenced by the North Atlantic Drift (an extension of the Gulf Stream), which transports warm water from the tropics toward the North Atlantic Ocean. This warm water releases heat into the atmosphere, contributing to London's relatively mild climate. Cities at similar latitudes but without access to warm ocean currents, like Ulaanbaatar, Mongolia, experience much colder temperatures.
2. Urban Heat Island Effect:
The urban heat island effect is a phenomenon where urban areas are significantly warmer than their surrounding rural areas. This is primarily due to the abundance of buildings, roads, and other infrastructure that absorb and retain heat from the sun during the day and release it slowly at night. London, being a densely populated city, experiences this effect, leading to higher average temperatures compared to nearby rural areas.
In addition to these two primary heat transfer processes, London also benefits from prevailing wind patterns that often bring warm air from the southwest. The city's location on the Thames Estuary also contributes to its relatively mild climate, as water tends to moderate temperature fluctuations.