Category Archives: Weather Dangers

How is a heat index determined?

The heat index (HI) indicates how hot it feels.

The HI is calculated using an equation that is a function of air temperature and the relative humidity. The HI is sometimes referred to as the “feels-like” temperature. Continue reading

Category: Meteorology, Severe Weather, Weather Dangers

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Can wildfires generate weather?

Fires require something to burn plus air to supply oxygen and a heat source to get the fuel to its ignition temperature.

Once a fire starts, weather is one factor of how it will spread and if it will grow. The important weather factors are temperature, wind and humidity. Warmer temperatures allow fuels to ignite quickly, and low humidity keeps the fuel dry and easy to burn. Wind brings oxygen to the fire and also can help to spread it. Continue reading

Category: Meteorology, Phenomena, Severe Weather, Weather Dangers

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Are we seeing more ozone advisories in southcentral Wisconsin?

Ozone (O3) is a molecule formed by three oxygen atoms.

Ozone that resides in the stratosphere absorbs ultraviolet rays of the sun, protecting life on Earth’s surface from these high-energy electromagnetic waves. O3 also can occur near the ground, where it is considered a pollutant, as it is a chemically reactive gas that can cause respiratory problems when breathed. Continue reading

Category: Climate, Phenomena, Weather Dangers

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Why was the sun so red this past week?

Light is a form of electromagnetic energy that does not need matter to propagate. We can characterize this energy by its wavelength, which is the distance along a wave from one crest to another. Our eyes are sensitive to light with wavelengths between approximately 0.4 to 0.7 microns. Blue colors have shorter wavelengths, while red colors have longer ones.

When light interacts with particles suspended in air, it can be scattered or absorbed. Energy that is scattered causes a change in direction of the light path. The amount of light that is being scattered is a function of the size of the particle relative to the wavelength of the light falling on the particle. While all colors are scattered by air molecules, violet and blue are scattered most. The sky looks blue, not violet, because our eyes are more sensitive to blue light. Continue reading

Category: Meteorology, Phenomena, Weather Dangers

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How could we be in a fire danger this early in spring after all the winter snow?

This 2022-23 winter — December through February — was exceptional in that it was Wisconsin’s wettest meteorological winter on record, and those records go back to 1895.

The state also experienced significant snowfall in March. When the snow slowly melts into the soil, it provides needed water for plant growth. Continue reading

Category: Climate, Seasons, Weather Dangers

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