Misc Hot and Cold

Question 1

Heat index

Answer 1

A key measure of heat
danger is the heat
index. Heat index
sometimes referred to
as ‘apparent
temperature’ because it
represents what the
atmosphere feels like
when relative humidity
is combined with air
temperature. The
inclusion of humidity in
the computation is
important because it
acknowledges that high
humidity inhibits the
body’s ability to cool
itself by the evaporation
of perspiration.

Question 2

Heat Wave

Answer 2

A heat wave is a prolonged period of excessively hot weather.

Question 3

Heat Advisory

Answer 3

A Heat Advisory is issued when the heat index value is expected to reach 100-105 °F (varies
somewhat by location) within the next 12 to 24 hours.

Question 4

Excessive Heat Warning

Answer 4

An Excessive Heat Warning is issued when the heat index value is expected to reach
105-115 °F (varies somewhat by location) within the next 12 to 24 hours.

Question 5

Physically hazards of heat

Answer 5

The first, more immediate hazard is hyperthermia, usually referred to as heat stroke. Heat stroke is an acute
medical emergency characterized by the failure of body functions, notably including the ability to dissipate heat. Once
started, hyperthermia progresses as a vicious cycle in which body temperature rises, body heat regulation begins to fail,
and body temperature rises further until organ systems fail.
Another hazard, less apparent but very significant, is increased mortality

Question 6

What causes heatwaves

Answer 6

Heat waves are generally caused by persistent, stationary atmospheric high-pressure systems. High-pressure
systems are characterized by descending air, which gets compressed and heated as it falls. The increasing
temperature decreases in relative humidity and suppresses cloud formation. (both of these effects are the
opposite of what happens with rising air, which causes stormy weather. Warming air, combined with clear skies
and bright sunshine leads to elevated temperatures in the air mass. If these conditions occur in the summer, the
elevated temperatures can reach hazardous levels.

Question 7

Red flag warning for wild fires

Answer 7

*Sustained 20 ft elevation Winds: >15 mph
*Relative Humidity: < 25%
*10 hr Dead Fuel Moisture: <9%

Question 8

Ground fires

Answer 8

fed by peat, duff, and other underground organic matter. While they may seem relatively benign, they
may smolder for long periods of time, and may at any time emerge as more rapidly progressing wildfires.

Question 9

Surface fires

Answer 9

burn low-lying vegetation, ground debris, and shrubs. These fires may travel fairly quickly, and under
favorable conditions may evolve into even larger, hotter, more dangerous types

Question 10

Ladder fires

Answer 10

an intermediate stage of wildfire development, as a surface fire begins to spread/grow upward in a tree
canopy.

Question 11

crown fires

Answer 11

occur when the entire vertical structure of a forest is fully engulfed in flames. These fires may spread very
rapidly due to extreme temperatures and the likelihood of spotting

Question 12

Blizzard characteristics and definition

Answer 12

A blizzard is a winter storm characterized by
large amounts of falling or blowing snow, high
winds, and low visibility which persists for an
extended period of time.
Note that while temperature is not an explicit
criterion for a blizzard, the presence of frozen
precipitation and high winds do lead to
dangerously low wind chills (apparent
temperatures).
The National Weather Service definition (used
for issuing watches and warnings) has three
parts:
*sustained winds of 35 miles per hour or
greater
*visibility of 1/4 mile or less
*lasting for at least three hou