1. What is the Heat Index Equation?

The Heat Index (HI) equation calculates how hot it feels when relative humidity is factored in with the actual air temperature. It provides a measure of the perceived temperature that accounts for the effects of humidity on human comfort and health.

2. How Does the Calculator Work?

The calculator uses the Rothfusz regression equation:

Where:

• \( T \) — Temperature in degrees Fahrenheit (°F)
• \( RH \) — Relative humidity percentage (%)
• \( HI \) — Heat index in degrees Fahrenheit (°F)

Explanation: The equation accounts for the non-linear relationship between temperature and humidity and how they combine to affect perceived temperature.

3. Importance of Heat Index Calculation

Details: The heat index is crucial for assessing heat-related health risks. Higher heat index values increase the risk of heat exhaustion and heat stroke, especially during physical activity.

4. Using the Calculator

Tips: Enter temperature in °F and relative humidity in %. Both values must be valid (temperature between 80-110°F for most accurate results, humidity between 0-100%).

5. Frequently Asked Questions (FAQ)

Q1: Why use this complex equation instead of a simple table?
A: The equation provides precise calculations for all combinations of temperature and humidity, while tables typically show rounded values for specific ranges.

Q2: What are dangerous heat index levels?
A: Caution is advised above 90°F, extreme caution above 103°F, and dangerous conditions exist above 125°F.

Q3: Does this work for temperatures below 80°F?
A: The equation is designed for temperatures ≥80°F. Below this, humidity has less impact on perceived temperature.

Q4: Are there limitations to this equation?
A: It assumes shady, light wind conditions. Full sunshine can increase heat index values by up to 15°F.

Q5: How does wind affect heat index?
A: The standard heat index doesn't account for wind. Strong winds can make it feel cooler despite high humidity.