Lämpösaareke

Lämpösaareke, or urban heat island (UHI) in English, is a phenomenon where urban areas experience significantly higher temperatures than surrounding rural areas. This temperature difference is most pronounced during the night and on clear days.

The primary cause of the urban heat island effect is the modification of the land surface by human activities. Buildings, roads, and other infrastructure materials, such as concrete and asphalt, absorb and retain more solar radiation than natural vegetation and soil found in rural landscapes. This stored heat is then released slowly into the atmosphere, contributing to higher temperatures. Additionally, reduced vegetation cover in cities means less shade and less evaporative cooling, further exacerbating the heat. Anthropogenic heat released from activities like industrial processes, vehicle emissions, and air conditioning also plays a role.

The consequences of urban heat islands can be significant. They can increase energy consumption as demand for air conditioning rises. Heat stress can negatively impact public health, particularly for vulnerable populations. Furthermore, increased temperatures can affect air quality by promoting the formation of ground-level ozone.

Mitigation strategies for the urban heat island effect include increasing green spaces, such as parks and green roofs, which provide shade and evaporative cooling. Using lighter-colored, reflective materials for buildings and pavements can also reduce heat absorption. Urban planning that incorporates water features and promotes airflow can also help to alleviate the phenomenon.