What is Haines Index in fire weather?
Haines (1988) developed the Lower Atmosphere Stability Index, or Haines Index, for fire weather use. It is used to indicate the potential for wildfire growth by measuring the stability and dryness of the air over a fire.
What does high Haines Index mean?
Haines Index (HI) Is a numerical value that indicates the potential for large wildfires to experience extreme fire behavior. The HI combines both the instability and dryness of the air by examining the lapse rate between two pressure levels in the atmosphere and the dryness of one of the pressure levels.
What does a high Haines of 6 mean?
A Haines Index of 6 means a high potential for an existing fire to become large or exhibit erratic fire behavior, 5 means medium potential, 4 means low potential, and anything less than 4 means very low potential.
What is a Haines 5?
Values of 2 or 3 are considered “Very Low,” a 4 is “Low,” a 5 is “Moderate” and a 6 is “High.” The use of “low” and “high” to describe both the value and the variant of the Haines Index can lead to some confusion, and users must be clear on which aspect they mean.
How is Haines calculated?
The Haines Index is the sum of a stability term and a moisture term. The sum provides an indication of the potential for the rate of spread (ROS) of a fire on a given day. A Haines Index of 2-3 = a very low ROS, 4 = low ROS, 5=moderate ROS, and 6 = high ROS.
Which would make the best safety zone?
How do you identify a good safety zone? Consider the distance from the escaped fire as well as topography, winds, fire behavior, and fuels in the area. The best locations are usually in the black, have with a minimum of, or are devoid of, ground/aerial vegetation, or are large bodies of water.
What does Decreasing cloudiness mean?
Increasing Cloudiness. Cloudiness increases within the period. Decreasing Cloudiness. Cloudiness decreases within the period. Becoming Partly Cloudy.
What does Haines mean?
Gender: Male. Origin: English. Meaning: Dweller By The Enclosure.
What is C Haines?
The C-Haines Index is a tool for evaluating the potential contribution of dry, unstable air to the development of large or erratic plume-dominated bushfires. • PyroCb is a tall, dense, fluffy cloud with a flat base and spreading anvil shaped head that is produced by the intense heating of air in a bushfire.
How far to separate firefighters from fuels?
The Incident Response Pocket Guide (IRPG) states that distance between the firefighter and the flames should be a minimum of four times the maximum continuous flame height. Distance separation equals the radius from the center of the safety zone to the nearest fuels.
How do you determine safety zone size?
A general rule of thumb can be derived from figure 1 by approxi- mating the injury limit with a straight line. After doing so, it appears that a safety zone should be large enough that the distance between the firefighters and flames is at least four times the maximum flame height.
What does 70 cloud cover look like?
Mostly cloudy (or broken) is classified as 70 to 80 percent cloud cover or five to seven oktas. This is less than the 90 to 100 percent (eight oktas) used to define overcast skies. On mostly cloudy days, you will be able to see separation in the clouds. On overcast days, the sky looks like one big cloud.
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