Extreme Heat Survival Guide: What Is The Real Temperature?
What is the Real Temperature? (Ambient, Radiant, Direct Solar Heat, Heat Index)
With all the different temperature index readings, which one really matters? At different times in the day the exact same temperature index reading does not accurately reflect the conditions or actual temperature at the locations we visit. On hot days, we often check the "temperature" index on our phones and base our expectations of our ability to "handle the heat" to ready ourselves before going out, based on those expectations. Oftentimes we rush out the door as we are late taking the kids to school or running late for work, without even considering the conditions. This article dives deeper into why it is unwise and at times dangerous to assume temperature readings are enough. It dispels the assumptions of heat, outlines the properties behind heat and unwraps that knowledge as to how that heat affects us. The article informs us of the indices and factors that really matter, our body's ability to manage heat and how we can implement simple practices to help prevent and protect us from overheating and becoming ill from the effects of extreme heat.
Different Sources of Heat
Temperature of the ambient air of the surrounding environment, is a measure of Ambient Heat. Radiant Heat refers to the heat energy emitted or infrared heat radiating from heat sources such as the sun, hot objects and surfaces and does not need air to transfer heat. Direct solar heat refers to ultraviolet radiation.
Radiant or Infrared Heat
Temperatures for specific locations are influenced by many external factors such as: air temperature, relative humidity, direct sunlight UV rays, radiant heat emitted from surrounding surfaces, such as buildings, ground materials and wind speed. High density urban areas, known as urban heat islands often experience higher radiant temperatures due to heat-absorbing materials like asphalt and concrete. These materials retain heat and radiate it back into the environment, exacerbating heat stress for city inhabitants. from the US EPA study "What are Heat Islands".
Direct Solar Ultraviolet Rays (UV)
OSHA - Exposure to direct sunlight significantly elevates the body's heat gain beyond what the heat index indicates. Studies have shown that damaging ultraviolet rays from direct solar radiation creates a higher heat load and can cause physiological heat stress at the same ambient temperature compared to shaded conditions. Direct exposure to sunlight and ultraviolet rays can increase thermal radiation absorbed by the body and elevate core temperatures by 15°F or 8.3°C compared to shaded areas.
Wet Bulb Globe Temperature Index (WBGT)
WBGT incorporates air temperature, humidity, wind speed and solar radiation and offers a general sense of perceived temperature, it does not fully capture the full impact of direct solar ultraviolet radiation. WBGT is commonly used in occupational health and sports to determine the risk of heat-related illnesses. It helps in establishing guidelines for activities in hot environments. Higher WBGT values indicate greater heat stress, prompting adjustments in work/rest and cooling cycles and hydration strategies.
Ultraviolet Index (UV Index)
Ultraviolet Index (UV Index) is a measure of the strength of ultraviolet (UV) radiation from the sun at a specific location and time. It ranges from 0 (minimal risk) to 11+ (extreme risk). The UV Index helps individuals understand the risk of harm from unprotected sun exposure. It indicates the need for protective measures like sunscreen, clothing, and shade to reduce the risk of skin damage and related health issues - skin, tissue damage and skin cancer.
Wet Bulb Globe Temperature index (WBGT) and the UV Index are the two important measurements used to assess environmental conditions, particularly in relation to heat stress and UV radiation exposure, especially during outdoor activities like sports or labor. High WBGT and high UV indicates potential heat stress. When planning outdoor activities, it’s essential to consider both indices: ensuring hydration and cooling measures in high WBGT and UV conditions while also taking additional precautions against UV radiation (e.g., wearing sunscreen and protective clothing).
Surface Temperature vs. Air Temperature (concrete, asphalt, grass, turf)
Open-air stadiums can literally become heat ovens, especially during midday games. Temperatures can easily reach 85°F to 100°F (29°C to 38°C) or higher during summer months, particularly in regions with high humidity. The heat can be exacerbated by direct sunlight, particularly if seating is exposed.
Depending on the surface such as turf or asphalt, on hot days surface temperatures can superheat the air near the ground, track, court or field and temperatures can be 30°F to 70°F higher than the air higher above. When the surface temperature reaches and rises above 115°F (46°C), it is considered extremely risky for athletes, as contact with the surface can lead to skin burns and melt shoes.
Concrete with its lighter color does not get as hot as asphalt during the day. Asphalt is darker in color, absorbs more heat from sunlight during the day and typically gets significantly hotter, sometimes reaching a temperature difference of up to 20°F (7°C). At night however, concrete retains more heat than concrete and at night can be slightly warmer than asphalt. Typical surface temperatures on hot sunny day:
- Concrete: 20°F to 150°F (49°C to 66°C)
- Turf: 120°F to 180°F (49°C to 82°C)
- Asphalt: 140°F to 190°F (49°C to 66°C)
Natural grass is the coolest surface due to its reflective green color properties and moisture transpiration. On a sunny day, grass typically has a temperature 70°F to 90°F (21°C to 32°C).
Body Temperature v. Surrounding Temperature
Temperatures in 80°F's are high enough to result in a Heat Index value of 90°F and cause heat stroke and death. Wet Bulb Globe Temperature Index and Ultraviolet Index are great indicators for getting clues as to what environment our bodies will have to overcome. Elevated core body temperatures are a result of many factors: surrounding air temperatures; relative humidity; air speed; radiant heat the surroundings; ground surface; direct sun ultraviolet rays; the heat reservoir of the enclosed space; physical exertion; clothing; and protective wear.
The real temperature that is of greatest importance is the temperature of the body's core. How we perform in extreme heat depends on our body's limits and how we mitigate the challenge of overheating to keep our body core at temperatures between 97°F and 99°F (36.1°C and 37.2°C).
Even with precautions, you may still experience heat stress. Cooling down quickly is essential to prevent long-term health risks. Krazy Kool TechnologyTM cold therapy solutions target the body core zones and is designed to give quick, all day effective heat prevention and protection against Heat Exposure - see Our Krazy Kool Science.
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Applying cold packs to target core body zones can quickly reduce body heat. Our revolutionary Krazy Kool TechnologyTM Cold Cores and Krazy Kool TechnologyTM were specifically designed to provide super long-lasting cold therapy throughout the day and are easy to use during cooling breaks, post-workout or post-workshift recovery.
2. Cold Therapy for Muscle Recovery
Heat stress can lead to muscle fatigue and inflammation. Using Krazy Kool TechnologyTM System cold therapy on sore muscles help reduce the cardiovascular load from overheating, reduce pain, swelling, and recovery time.
3. Wearable Cooling Solutions for On-the-Go Relief
Our innovative Krazy Kool TechnologyTM System offers versatile cold therapy to individual core body zones for continuous temperature regulation and stabilization and help you minimize the risks, stay cool and comfortable.
