Heavy snow, significant ice accumulations, and blizzard conditions are likely across parts of the Northern Plains into the Upper Great Lakes. South of the winter weather, a regional outbreak of severe storms with some flash flooding is expected across parts of the Mid-Mississippi Valley and Mid-South into the Ohio Valley. Gusty winds may bring critical fire weather to the Central/Southern Plains. Read More >
Density Altitude: The altitude in the standard atmosphere at which the air has the same density as the air at the point in question. An aircraft will have the same performance characteristics as it would have in standard atmosphere at this altitude.
High Density Altitude: A condition of the atmosphere that reduces an aircraft’s performance capability to below a level of standard performance at a specified altitude.
Cold, Dry Day![]() Low Density Altitude |
Hot, Humid Day![]() High Density Altitude |
Air density is determined by Pressure, Temperature, and Humidity.
On a hot, muggy day, the air becomes "thinner" or less dense, and its density at a pilot's location is equivalent to a higher altitude in the standard atmosphere. Thus the term "high density altitude."
Pilots must determine if high density altitude will impact their flight by calculating density altitude and checking their aircraft performance charts.
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