The Science of Comfort in Thermal Environments: From Wet-Bulb Temperatures to Ultraviolet Indices and La Niña Effects

When water evaporates from a surface, it cools the surface by taking away heat. The wet-bulb temperature is the lowest temperature that can be achieved through this process and is defined in thermodynamic terms. It can be easily measured using a shielded thermometer exposed to air but not direct sunlight. This temperature is used to evaluate comfort in a thermal environment.

The amount of moisture that air can hold depends on the temperature, with warmer air being able to hold more moisture. This concept is related to global warming and the formation of wetter cyclones. The relative humidity refers to the amount of moisture in air adjusted for the maximum it can hold at a specific temperature. When air reaches its dew point, it becomes 100% saturated with moisture.

In 1992, scientists developed the Ultraviolet Index (UV Index) which was adopted by the World Health Organisation and World Meteorological Organisation in 1994. This index measures solar radiation on a scale, with lower values indicating less harm to skin and higher values posing risks such as sunburn, DNA damage, and cataracts.

La Niña is a weather phenomenon characterized by a band of cool water stretching from east to west across the equatorial Pacific Ocean.