Dry bulb temperature is the ambient temperature. It is measured in degrees, from a mercury thermometer with a scale of Fahrenheit or Celsius. The dry bulb temperature should be measured in an area away from direct sunlight.

Chapter 7 describes the key weather factors referenced in the field, namely temperature and relative humidity. The chapter content includes information on dry bulb and wet bulb temperatures, dew point, and using a psychrometric table to determine the moisture content of the air.

A bearing provides a direction given as the primary compass direction (north or south), degree of angle, and an east or west designation. A bearing describes a line as heading north or south, and deflected some number of degrees toward the east or west. A bearing, therefore, will always have an angle less than 90°.

Example 1 - Megan starts at a point and goes in the direction shown in the figure below. What is her bearing?

Megan is in the NE quadrant. The primary compass direction is north. Count the degrees down from North, for a total of 70°. 

Chapter 6 provides information on finding your current location by using bearing, azimuth, back azimuths, a compass, and a map. It describes techniques for correcting for declination and explains intersection, resection, latitude, and longitude. Additional information highlights Global Positioning Systems (GPS), base, townships, range, and sections.

The perimeter is the distance around the fire or along the handline. Perimeter is determined by adding the lengths of the various lines that enclose the black area of a fire. Because fires often burned in unusual shapes such as fingers, the perimeter of a fire can be approximated by assembling a combination of known shapes and lines. 

The material in Chapter 5 describes calculating area and perimeter of a burn, fire spread distance, and effective windspeed. Detailed descriptions are provided for reading and using a map scale, converting map to ground distances, and using topographic maps.

Flame height is the average height of flames as measured vertically, up and down. It may be less than flame length if the flames are angled in the horizontal direction, backward or forward. 
 

Flame length is the distance measured from the average flame tip to the middle of the flaming zone at the base of the fire. It is measured on a slant when the flames are tilted due to effects of wind and slope. Flame length is an indicator of fireline intensity.

The material in Chapter 4 describes estimates of flame length, flame height, angles, degrees, and slopes. Reading clinometers and graphs and pacing out a chain are also covered.

Volume is used to indicate the capacity of a tank or container. It is used by firefighters to answer questions like "How much water is left in the tank?" and "At 15 gallons per minute (gpm), how many more minutes before the tank is empty?" 

VOLUME OF A RECTANGULAR OBJECT

The volume of a rectangular container is determined by multiplying the length (l) by the width (w) by the height (h).