Temperature
 a measure of the average
speed at which molecules are
moving or vibrating.
Temperature scales
Freeze
Boil
Celsius
0
100
Fahrenheit
32
212
Kelvin
273
373
Conversions
►oF
= (1.8 x oC) + 32
►oC = 0.56 (oF – 32)
►K = oC + 273
What Controls temperature?
1. Insolation differences
(latitudinal , seasonal, daily)
2. Proximity to water bodies
(land/water distribution)
3. Elevation
4. Ocean currents
5. Cloud Cover
1. Insolation
a. Latitudinal
► High
latitudes receive less insolation than low
latitudes because…
 sun’s rays are more oblique
 Day length is variable
 Net energy surplus in tropics; net energy
deficit in polar regions
demonstrate
b. Seasonal
Changing angle of sun throughout the
year changes temperature on a seasonal
basis.
c. Daily (diurnally)
Changing angle of sun throughout the day
changes temperature on a daily basis.
Diurnal temperature pattern
Temperature increases
as long as net all wave
incoming exceeds net
all wave outgoing.
Min: end of deficit
Max: end of surplus
2. Proximity to water bodies
► Water
bodies have a moderating effect
on temperature.
 Maritime locations (coastal, island) have smaller
daily and annual ranges in temp than
continental locations
demonstration
► Small
effect from Lake Superior on Duluth
temperatures
 Warmer winters, cooler summers near lake vs
inland
 Top of the hill vs. harbor
►Harbor
warmer in fall; cooler in spring
►Extreme example (May 2009)
3. Elevation
► Temperature
decreases as elevation
increases.
 less mass, less pressure, less
absorption
► Review:
► Factors
place:
affecting the air temperature of a
►Insolation
differences at various latitudes, during
seasons, during the course of a day
►Proximity to big water bodies
►Elevation
►Ocean currents
►Cloud cover
5. Cloud Cover
► Exert
influence on shortwave and longwave
exchanges:
 Very efficient absorbers and emitters of
longwave
 Reduce incoming shortwave
►High
albedo
► Net
Result:
 Dampen diurnal temp range
►Cloudy:
uniform temps, small diurnal range
►Clear:
daytime high insolation and nighttime loss of
longwave; large diurnal range
About cloud measurement
Temperature and Human Comfort
 Comfort range: air temperature 68 - 77°F
 Outside comfort range, body will:
►Perspire
►Shiver
►Restrict/increase
flow of blood to skin
Humans are homeothermic
Body regulates core temperature to
within 3.6°F of 98.6° (95- 102.2)
►Hypothermia: Core drops below
95°F





Violent shaking
Lethargy
Impaired speech
Blurred vision
Clumsy
Degree of
Hypothermia
Signs and
Symptoms
Cardio-respiratory
Response
Level of
Consciousness
95 F - Mild
Shivering
Foot Stomping
Normal
Withdrawn
90 F - Mild
Loss of
Coordination
Normal to Impaired
Confused
85 F - Moderate
Lethargy
Slow Pulse
Sleepy
80 F - Severe
Coma
Weak Pulse Slow
Respirations
Irrational if
Conscious
78 F - Severe
Apparent Death
V-Fib/Cardiac Arrest
Unconscious
Alcohol adds to danger
ingestion increases the risk of
acquiring or aggravating hypothermia by
causing cutaneous vasodilation (which
prevents vasoconstriction), impairment of
the shivering mechanism, hypothalamic
dysfunction, and a decrease in awareness of
environmental conditions”.
► “Alcohol
treatment
►
►
►
►
►
►
►
►
Call 911
Get victim to warm place; otherwise don’t move them
Remove wet clothing; replace with dry but minimize movement
of person
Warm core first before extremities
Skin-to-skin contact in blanket or sleeping bag
Do NOT RUB SKIN
If victim can eat, give sweet food or drink (no alcohol or
caffeine)
Don’t elevate legs
 Legs are holding cold blood that would return to heart if legs are
elevated
►
Don’t give CPR unless not breathing or no pulse
 Victim may appear dead but can be resuscitated
Frostnip vs. frostbite
About 4,800 cases of frostbite occur in the United States each year.
Frostnip is mild form of frostbite
► skin looks pale and feels cold, numb and stiff
► Yellowish or white
► underlying tissues remain warm and flexible
► uncomfortable but doesn’t lead to blisters, scarring or
permanent damage
► minor but could lead to frostbite
►
Second degree frostbite
►
►
white or blue skin; feels
hard and frozen.
blisters after rewarming
Third degree frostbite
► Tissue freezes
► Skin turns white, blue,
black or mottled
► tissues beneath the skin
feel hard and frozen.
► Deep tissue damage to
blood vessels, nerves,
tendons, muscle
► May require amputation
Water immersion
► Can
lead to hypothermia much more rapidly
than simple cold temperatures
► Because
than air
water is a better conductor of heat
Ice safety
Wind chill
► Indoors:
 Body loses heat by
►Net
radiation (60%)
►Evaporation from lungs, skin (25%)
► Outdoors:
 Body loses heat by
►Radiation
►Evaporation
►AND
convection
Wind chill equivalent temperature
(W.E.T.)
► Temperature
in still air that would
correspond to the cooling generated by the
combination of temperature and wind
 Body loses heat at a rate equivalent to
conditions induced by calm winds at W.E.T.
Hyperthermia
► Core





goes above 102ºF
Collapse
Cramps
Unconscious
Stop sweating
Headache, nausea, fatigue
treatment
► Cool
place
► Liquids (not alcohol or
caffeine)
► Shower, bathe, sponge off
with cool water
► rest
Heat Stroke
► Temp
> 104ºF
► confusion, combativeness, bizarre behavior
► faintness, staggering
► strong rapid pulse
► dry flushed skin, lack of sweating
► possible delirium or coma
Heat Index
► Gauges
combined effects of temperature
and humidity; advise danger of heat stress
 Comfort depends on ability to lose heat through
evaporation
►Need
vapor pressure gradient between skin and air
►Evaporative cooling decrease as humidity increases
► Index:
gives apparent temperature
 Temperature in dry air that would cause same
level of discomfort
Temperature inversion
Annual March of the Seasons