The “feels like” temperature describes how atmospheric conditions are perceived by the human body, distinct from the actual air temperature. This subjective sensation arises because various environmental elements, beyond just air temperature, interact with our physiological responses. Factors like wind and humidity significantly modify how hot or cold it truly feels, making this distinction important for comfort and safety.
How Wind Changes Perception
Wind plays a significant role in how cold the air feels, a phenomenon known as wind chill. When wind blows across exposed skin, it continuously removes the thin layer of warm air the body naturally heats, accelerating heat loss through convection. This makes temperatures feel much colder than indicated; for example, 35 degrees Fahrenheit with a 25 mph wind can feel as cold as 8 degrees Fahrenheit. Wind chill affects living organisms by increasing heat loss, but it does not cool inanimate objects below the actual air temperature. The wind chill index, updated in 2001, quantifies this effect by modeling heat transfer from exposed skin.
The Effect of Humidity
Humidity profoundly influences how warm temperatures are perceived, leading to the concept of the “heat index.” The human body primarily cools itself through the evaporation of sweat from the skin’s surface. However, high humidity means the air already contains a significant amount of water vapor, reducing its capacity to absorb additional moisture from the skin, which hinders the body’s natural cooling and makes warm temperatures feel more oppressive. Conversely, in very low humidity, sweat evaporates more quickly, which can make hot temperatures feel less intense. The heat index combines air temperature and relative humidity to provide a more accurate representation of how hot it feels outdoors.
Beyond Wind and Humidity
Several other environmental factors also contribute to the perceived temperature. Direct solar radiation, or sunshine, significantly increases how warm a person feels, even if the air temperature remains constant, as the sun’s energy is absorbed by the body. Cloud cover, on the other hand, reduces this direct solar radiation, making conditions feel cooler. Radiant heat from surfaces also plays a role; materials like asphalt and concrete absorb solar energy and then re-radiate it, warming the surrounding environment, especially in urban areas. Factors like atmospheric pressure and altitude can subtly influence thermal comfort by affecting air density and oxygen levels, which in turn impact physiological responses to temperature.
Why Individuals Feel Differently
Even when exposed to identical environmental conditions, individuals often experience temperature differently due to a range of personal factors. Clothing choices, for instance, directly impact insulation and heat retention or dissipation. An individual’s activity level also influences their internal heat production; a person exercising will feel warmer than someone at rest in the same environment.
Metabolism, the rate at which the body converts food into energy, affects core body temperature and, consequently, thermal perception. Differences in body fat percentage provide varying levels of insulation, with higher body fat generally leading to a greater tolerance for cold. Age can also play a role, as older adults may have different thermoregulatory responses. Health conditions and acclimatization, or how accustomed someone is to a particular climate, further contribute to the subjective experience of temperature.