1. Thermal comfort – definition;
main indices used to express
thermal comfort and heat
stress. General approaches to
measurement of temperature,
humidity and air velocity
2. Thermal comfort is a term used by the
American Society of Heating, Refrigerating
and Air-Conditioning Engineers, an
international body. It is defined as the state
of mind in humans that expresses
satisfaction with the surrounding
environment (ANSI/ASHRAE Standard 55).
Maintaining this standard of thermal
comfort for occupants of buildings or other
enclosures is one of the important goals of
HVAC (heating, ventilation, and air
conditioning) design engineers.
Thermal comfort
3. Thermal comfort is affected by heat
conduction, convection, radiation, and
evaporative heat loss. Thermal comfort
is maintained when the heat generated
by human metabolism is allowed to
dissipate, thus maintaining thermal
equilibrium with the surroundings. It
has been long recognised that the
sensation of feeling hot or cold is not
just dependent on air temperature
alone.
Thermal comfort
4. Thermal discomfort has been known to
lead to Sick Building Syndrome
symptoms. The combination of high
temperature and high relative humidity
serves to reduce thermal comfort and
indoor air quality. The occurrence of
symptoms increased much more with
raised indoor temperatures in the winter
than in the summer due to the larger
difference created between indoor and
outdoor temperatures.
Importance of thermal comfort
6. General Factors
Air temperature
Mean radiant temperature
Relative humidity (see
also perspiration)
Drifts and ramps in
operative temperature
Factors determining thermal
comfort
include
7. Localized factors
Air movement/velocity (see
wind chill factor)
Radiant asymmetry
Floor surface temperatures (see
underfloor heating)
Air temperature stratification
Factors determining thermal
comfort
include
8. When measuring metabolic rates, many
factors have to be taken into account.
Each person has a different metabolic
rate, and these rates can fluctuate when
a person is performing certain activities,
or under certain environmental
conditions. Even people who are in the
same room can feel significant
temperature differences due to their
metabolic rates, which makes it very
hard to find an optimal temperature for
everyone in a given location.
Metabolism
9. Food and drink habits may
have an influence on
metabolic rates, which
indirectly influences thermal
preferences. These effects
may change depending on
food and drink intake.
Metabolism
10. Body shape is another factor that
affects thermal comfort. Heat
dissipation depends on body surface
area. A tall and skinny person has a
larger surface-to-volume ratio, can
dissipate heat more easily, and can
tolerate higher temperatures than a
more rounded body shape.
Metabolism
11. During cold weather, layers of insulating
clothing can help keep a person warm.
At the same time, if the person is doing
a large amount of physical activity, lots
of clothing layers can prevent heat loss
and possibly lead to overheating.
Generally, the thicker the garment is the
greater insulating abilities it has.
Depending on the type of material the
clothing is made out of, air movement
and relative humidity can decrease the
insulating ability of the material.
Clothing insulation
12. The amount of clothing is measured
against a standard amount that is
roughly equivalent to a typical business
suit, shirt, and undergarments. Activity
level is compared to being seated
quietly, such as in a classroom. This
standard amount of insulation required
to keep a resting person warm in a
windless room at 70 °F (21.1 °C) is
equal to one clo.
Clothing insulation
13. Clo units can be converted to R-value
in SI units (m²·K/W) or RSI) by
multiplying clo by 0.155 (1 clo =
0.155 RSI). (In English units 1 clo
corresponds to an R-value of 0.88
°F·ft²·h/Btu.) ASHRAE 55-2004
mentioned a Table B1 and Table B2
for more clothing information.
Clothing insulation
14. The human body has sensors that are
fairly efficient in sensing heat and
cold, but they are not very effective in
detecting relative humidity. Relative
humidity creates the perception of an
extremely dry or extremely damp indoor
environment. This can then play a part in
the perceived temperature and their
thermal comfort. The recommended
level of indoor humidity is in the range
of 30-60%.
Relative humidity
15. A way to measure the amount of relative
humidity in the air is to use a system of dry-
bulb and wet-bulb thermometers. A dry-
bulb thermometer measures the
temperature not relative to moisture. This is
generally the temperature reading that is
used in weather reports. In contrast, a wet-
bulb thermometer has a small wet cloth
wrapped around the bulb at its base, so the
reading on that thermometer takes into
account water evaporation in the air.
Relative humidity
16. The wet-bulb reading will thus always
be at least slightly lower than the dry
bulb reading. The difference between
these two temperatures can be used
to calculate the relative humidity. The
larger the temperature difference
between the two thermometers, the
lower the level of relative humidity.
Relative humidity
17. The wettedness of skin in different
areas also affects perceived thermal
comfort. Humidity can increase
wetness on different areas of the
body, leading to a perception of
discomfort. This is usually localized in
different parts of the body and local
thermal comfort limits for local skin
wettedness differ between different
skin locations of the body.
Relative humidity
18. The extremities are much more
sensitive to thermal discomfort from
wetness than the trunk of the body.
Although local thermal discomfort
can be caused from wetness, the
thermal comfort of the whole body
will not be affected by the wetness of
certain parts.
Relative humidity
19. Recently, the effects of low relative
humidity and high air velocity were
tested on humans after bathing.
Researchers found that low relative
humidity engendered thermal discomfort
as well as the sensation of dryness and
itching. It is recommended to keep
relative humidity levels higher in a
bathroom than other rooms in the house
for optimal conditions.
Relative humidity
20. The concept of thermal comfort is
closely related to thermal stress. This
attempts to predict the impact of
solar radiation, air movement, and
humidity for military personnel
undergoing training exercises or
athletes during competitive events.
Values are expressed as the Wet Bulb
Globe Temperature or Discomfort
Index.
Thermal stress
21. Generally, humans do not perform well
under thermal stress. People’s
performances under thermal stress is
about 11% lower than their
performance at normal thermal
conditions. Also, human performance in
relation to thermal stress varies greatly
by the type of task you are completing.
Some of the physiological effects of
thermal heat stress include increased
blood flow to the skin, sweating, and
increased ventilation.
Thermal stress
22. The body has several thermal
adjustment mechanisms to survive in
drastic temperature environments. In a
cold environment the body utilizes
vasoconstriction; which reduces blood
flow to the skin, skin temperature and
heat dissipation. In a warm
environment, vasodilation will increase
blood flow to the skin, heat transport,
and skin temperature and heat
dissipation.
Adjustment mechanisms
23. If there is an imbalance despite the
vasomotor adjustments listed above, in a
warm environment sweat production will
start and an evaporative cooling mechanism
will be provided. If this is insufficient,
hyperthermia will set in, body temperature
may reach 40∘C and heat stroke may occur.
In a cold environment shivering will start,
involuntarily forcing the muscles to work
and increasing the heat production by up to
a factor of 10. If equilibrium is not restored,
hypothermia will set in which, can be fatal.
Adjustment mechanisms
24. Long term adjustments to extreme
temperatures of a few days to 6 months
may result in cardiovascular and endocrine
adjustments. A hot climate may create
increased blood volume, improving the
effectiveness of vasodilation, enhanced
performance of the sweat mechanism, and
the readjustment of thermal preferences. In
cold or underheated
conditions, vasoconstriction can become
permanent resulting in decreased blood
volume, and increased body metabolic rate.
Adjustment mechanisms
25. Many buildings use a HVAC (Heating
Ventilation Air Conditioning) unit to
control their thermal environment.
Recently, with the current energy and
financial situation, new methods for
indoor temperature control are being
used. One of these is natural
ventilation.
Effects of natural ventilation of
thermal comfort
26. This process can make the controlled
indoor air temperature more susceptible
to the outdoor weather, and during the
seasonal months the temperatures
inside can become too extreme. During
the summer months, the temperature
inside can rise too high and cause the
need for open windows and fans to be
used. In contrast, the winter months
could call for more insulation and
layered clothing to deal with the less
than ideal temperatures.
Effects of natural ventilation of
thermal comfort
27. The ideal standard for thermal comfort
can be defined by the operative
temperature. This is the average of the
air dry-bulb temperature and of the
mean radiant temperature at the given
place in a room. In addition, there
should be low air velocities and no
'drafts,' little variation in the radiant
temperatures from different directions
in the room, and humidity within a
comfortable range.
Operative temperature
28. The operative temperature
intervals varied by the type of
indoor location. They also vary
by the time of year. ASHRAE has
listings for suggested
temperatures and air flow rates
in different types of buildings
and different environmental
circumstances.
Operative temperature
29. For example, a single office in a building
has an occupancy ration per square
meter of 0.1. In the summer the
suggested temperature is between 23.5
(74.3 F) and 25.5 degrees Celsius (77.9
F) , and airflow velocity of 0.18 m/s. In
the winter, the recommended
temperature is between 21.0 and 23.0
degrees Celsius with an airflow velocity
of 0.15 m/s.
Operative temperature
30. The thermal sensitivity of an individual is
quantified by the descriptor FS, which
takes on higher values for individuals
with lower tolerance to non-ideal
thermal conditions. This group includes
pregnant women, the disabled, as well
as individuals whose age is below 14 or
above 60, which is considered the adult
range. Existing literature provides
consistent evidence that sensitivity to
hot and cold surfaces declines with age.
Thermal sensitivity of individuals
Cold sensitivity
31. There is also some evidence of a gradual
reduction in the effectiveness of the
body in thermoregulation after the age
of 60. This is mainly due to a more
sluggish response of the counteraction
mechanisms in the body that are used to
maintain the core temperature of the
body at ideal values.
Situational factors include the
health, psychological, sociological and
vocational activities of the persons.
Thermal sensitivity of individuals
Cold sensitivity
32. While thermal comfort preferences
between genders seems to be
small, there are some differences.
Studies have found men report
discomfort due to rises in
temperature much earlier than
women. Men also estimate higher
levels of their sensation of
discomfort than women
Gender differences
33. One recent study tested men and
women in the same cotton
clothing, performing mental jobs
while using a dial vote to report their
thermal comfort to the changing
temperature. Many times, females
will prefer higher temperatures. But
while females were more sensitive to
temperatures, males tend to be more
sensitive to relative humidity levels.
Gender differences
34. The adaptive model states that there is an
optimal temperature for a given indoor
environment depending on the outdoor air
temperature. It takes into account that humans
can adapt and tolerate different temperatures
during different times of the year. The optimal
temperature for a given time is determined by
looking at the mean outdoor temperatures of
each month of the year. Also, field studies are
performed in these areas to see what the
majority of people would prefer as their set-
point temperature indoors at different times of
the year.
Models of thermal comfort
When discussing thermal comfort, there are two different
models that can be used. These are the static model and the
adaptive model.
35. On the other side, the static model
states that the indoor temperature
should not change as the seasons do.
Rather, there should be one set
temperature year-round. This is
taking a more passive stand that
humans do not have to adapt to
different temperatures since it will
always be constant.
Models of thermal comfort
36. More advanced research
on thermal comfort
considers the heat
balance of the human
body and calculates
sensation and comfort for
local body parts.
Models of thermal comfort
37. In different areas of the world, thermal
comfort needs may vary based on climate.
In China there are hot humid summers and
cold winters causing a need for efficient
thermal comfort. Energy conservation in
relation to thermal comfort has become a
large issue in China in the last several
decades due to rapid economic and
population growth. Researchers are now
looking into ways to heat and cool buildings
in China for lower costs and also with less
harm to the environment.
Thermal comfort in different
regions
38. In tropical areas of
Brazil, urbanization is causing a
phenomenon called urban heat
islands (UHI). These are urban
areas, which have risen over the
thermal comfort limits due to a large
influx of people and only drop within
the comfortable range during the
rainy season.
Thermal comfort in different
regions
39. Urban Heat Islands can occur over any urban city or
built up area with the correct conditions. Urban Heat
Islands are caused by urban areas with few trees
and vegetation to block solar radiation or carry out
evapotranspiration, many structures with a large
proportion of roofs and sidewalks with low
reflectivity that absorb heat, high amounts of
ground-level carbon dioxide pollution that retains
heat released by surfaces, great amounts of heat
generated by air conditioning systems of densely
packed buildings and large amount of automobile
traffic generating heat from engines and exhaust.
Thermal comfort in different
regions
40. In the hot humid region of Saudi Arabia, the
issue of thermal comfort has been important in
mosques where Muslims (followers of
Islam, the only religion allowed to operate
publicly in Saudi Arabia, according to the
Shariah) go to pray. They are very large open
buildings which are used only intermittently
(very busy for the obligatory noon prayer on
Fridays) making it hard to ventilate them
properly. The large size requires a large amount
of ventilation but this requires a lot of energy
since the buildings are used only for short
periods of time.
Thermal comfort in different
regions
41. Some mosques have the issue of being
too cold from their HVAC systems
running for too long and others remain
too hot. The stack effect also comes into
play due to their large size and creates a
large layer of hot air above the people in
the mosque. New designs have placed
the ventilation systems lower in the
buildings to provide more temperature
control at ground level. Also new
monitoring steps are being taken to
improve the efficiency.
Thermal comfort in different
regions
42. Although thermal comfort of humans is the
main focus of thermal comfort studies, the
needs of livestock must be met as well for
better living and production. The
Department of Animal Production in Italy
produced a study on ewes, which tested
rumen function and diet digestibility of
ewes chronically exposed to a hot
environment. These two bodily functions
were reduced by the hot temperatures
offering insight that thermal comfort levels
are important to livestock productivity.
Thermal comfort of livestock
43. These factors were explored experimentally in
the 1970s. Many of these studies led to the
development and refinement of ASHRAE
Standard 55 and were performed at Kansas
State University by Ole Fanger and others.
Perceived comfort was found to be a complex
interaction of these variables. It was found that
the majority of individuals would be satisfied by
an ideal set of values. As the range of values
deviated progressively from the ideal, fewer and
fewer people were satisfied. This observation
could be expressed statistically as the % of
individual who expressed satisfaction by
comfort conditions and the predicted mean vote
(PMV)
Research
44. This research is applied to create Building Energy
Simulation (BES) programs for residential
buildings. Residential buildings can vary much
more in thermal comfort than public and
commercial buildings. This is due to their smaller
size, the variations in clothing worn, and different
uses of each room. The main rooms of concern are
bathrooms and bedrooms. Bathrooms need to be
at a temperature comfortable for a human with or
without clothing. Bedrooms are of importance
because they need to accommodate different
levels of clothing and also different metabolic
rates of people asleep or awake.
Research
45. Thermal comfort research in clothing
is currently being done by the
military. New air-ventilated garments
are being researched to improve
evaporative cooling in military
settings. Some models are being
created and tested based on the
amount of cooling they provide.
Research
46. Drill a hole in the overhead of the wheelhouse, sufficiently large to
pass the cable from the impeller to the wind-display unit. Run the
cable from inside the wheelhouse up to the planned location for the
impeller. Place the anemometer's impeller as high as possible in your
boat. The ideal location will be unobstructed for a full 360
degrees, and above all other instruments or sensors, such as radar or
GPS antennae.
Run the cable through the 34mm tubing and connect it to the impeller
using the screw connector on the end of the cable. Use the hose
clamps to lightly clamp the 34mm-diameter tube to the mast or a rail
on the uppermost part of the superstructure of the vessel. Insert the
mounting journal of the impeller into the tube and use the screwdriver
to tighten the hose clamps to secure the impeller in place.
Use the wire ties to secure the cable to the mast or rail so that the
cable follows the shortest route, but is secured against flapping and
wind damage.
How to Measure Air Velocity
The Fixed Anemometer
47. Connect the leads from the wind-display device to
the common power bus and common ground. The
wind-display unit is a reference device only. It
should not obscure equipment that will be used
frequently, like radar or the VHF/GMDSS bridge-to-
bridge radio.
Connect the cable from the impeller to the wind-
display device and, if necessary, secure the cable to
available surfaces and appliances with wire ties to
prevent tripping hazards. Apply marine silicone caulk
around the hole in the wheelhouse overhead on both
the inside and outside surfaces.
After the silicone caulk has cured in accordance with
the manufacturer's directions, it may be painted.
The wind-display unit will display both wind speed
and direction.
How to Measure Air Velocity
The Fixed Anemometer
48. Find a location aboard the boat that is
both high enough to hold the impeller
where it will not be obstructed from
the apparent direction of the
wind, and secure enough to provide
good footing.
Hold the impeller into the wind.
Read the wind velocity and direction
from the digital display panel on the
anemometer.
How to Measure Air Velocity
The Handheld Anemometer
50. Humidity is a term for the amount of
water vapor in the air, and can refer
to any one of several measurements
of humidity. Formally, humid air is
not "moist air" but a mixture of water
vapor and other constituents of
air, and humidity is defined in terms
of the water content of this
mixture, called the Absolute
humidity.
Humidity
51. In everyday usage, it commonly
refers to relative
humidity, expressed as a percent
in weather forecasts and on
household humidistats; it is so
called because it measures the
current absolute humidity
relative to the maximum.
Humidity
52. Specific humidity is a ratio of the
water vapor content of the
mixture to the total air content
(on a mass basis). The water
vapor content of the mixture can
be measured either as mass per
volume or as a partial
pressure, depending on the
usage.
Humidity
53. In meteorology, humidity indicates
the likelihood of
precipitation, dew, or fog. High
relative humidity reduces the
effectiveness of sweating in
cooling the body by reducing the
rate of evaporation of moisture
from the skin. This effect is
calculated in a heat index
table, used during summer
weather.
Humidity
54. If all the water vapor in one cubic meter
of air were condensed into a
container, the mass of the water in the
container could be measured to
determine absolute humidity.
Absolute humidity ranges from 0 grams
per cubic meter in dry air to 30 grams
per cubic meter (0.03 ounce per cubic
foot) when the vapor is saturated at 30
°C.
The absolute humidity changes as air
pressure changes.
Absolute humidity
55. Relative humidity is a term used to
describe the amount of water vapor
in a mixture of air and water vapor. It
is defined as the ratio of the partial
pressure of water vapor in the air-
water mixture to the saturated vapor
pressure of water at those conditions.
The relative humidity of air depends
not only on temperature but also on
pressure of the system of interest.
Relative humidity
56. Specific humidity is the ratio
of water vapor to dry air in a
particular mass, and is
sometimes referred to as
humidity ratio. Specific
humidity ratio is expressed as
a ratio of grams of water
vapor, mv, per kilogram of dry
air ma .
Specific humidity
57. Humidity is one of the fundamental
abiotic factors that defines any
habitat, and is a determinant of which
animals and plants can thrive in a
given environment.
Effects
Animals and plants
58. The human body dissipates heat by a
perspiration and evaporation. Heat
convection to the surrounding
air, and thermal radiation are the
primary modes of heat transport from
the body. Under conditions of high
humidity, the rate of evaporation of
sweat from the skin.
Effects
Animals and plants
59. Also, if the atmosphere is as warm as or
warmer than the skin during times of high
humidity, blood brought to the body surface
cannot dissipate heat by conduction to the
air, and a condition called hyperpyrexia
results. With so much blood going to the
external surface of the body, relatively less
goes to the active muscles, the brain, and
other internal organs. Physical strength
declines, and fatigue occurs sooner than it
would otherwise. Alertness and mental
capacity also may be affected, resulting in
heat stroke or hyperthermia.
Effects
Animals and plants
60. Humans are sensitive to humid air
because the human body uses
evaporative cooling as the primary
mechanism to regulate temperature.
Under humid conditions, the rate at
which perspiration evaporates on the
skin is lower than it would be under arid
conditions. Because humans perceive
the rate of heat transfer from the body
rather than temperature itself, we feel
warmer when the relative humidity is
high than when it is low
Human comfort
61. Some people experience difficulty
breathing in high humidity
environments. Some cases may
possibly be related to respiratory
conditions such as asthma, while
others may be the product of anxiety.
Sufferers will often hyperventilate in
response, causing sensations of
numbness, faintness, and loss of
concentration, among others.
Human comfort
62. Air conditioning works by
reducing humidity in
summer. In winter, heating
cold outdoor air can decrease
relative humidity levels
indoor to below 30%, leading
to discomfort such as dry
skin and excessive thirst.
Human comfort
63. Many electronic devices have humidity
specifications, for example, 5% to 95%.
At the top end of the range, moisture
may increase the conductivity of
permeable insulators leading to
malfunction. Too low humidity may
make materials brittle. A particular
danger to electronic items, regardless of
the stated operating humidity range, is
condensation
Electronics
64. Traditional building designs typically had
weak insulation, and it allowed air
moisture to flow freely between the
interior and exterior. The energy-
efficient, heavily-sealed architecture
introduced in the 20th century also
sealed off the movement of
moisture, and this has resulted in a
secondary problem of condensation
forming in and around walls, which
encourages the development of mold
and mildew.
Building construction
65. A hygrometer is a device used for
measuring the humidity of the air
Measurement
66. There are various devices used to
measure and regulate humidity. A
device used to measure humidity is
called a psychrometer or hygrometer.
A humidistat is used to regulate the
humidity of a building with a
dehumidifier. These can be analogous
to a thermometer and thermostat for
temperature control.
Measurement
67. Humidity is also measured on a global scale
using remotely placed satellites. These satellites
are able to detect the concentration of water in
the troposphere at altitudes between 4 and 12
kilometers. Satellites that can measure water
vapor have sensors that are sensitive to
infrared radiation. Water vapor specifically
absorbs and re-radiates radiation in this
spectral band. Satellite water vapor imagery
plays an important role in monitoring climate
conditions (like the formation of
thunderstorms) and in the development of
future weather forecasts.
Measurement
68. A hygrometer (UK: /haɪˈɡrɒmɪtə/) is an
instrument used for measuring the moisture
content in the environmental air, or
humidity. Most measurement devices
usually rely on measurements of some
other quantity such as
temperature, pressure, mass or a
mechanical or electrical change in a
substance as moisture is absorbed.
Modern electronic devices use temperature
of condensation, or changes in electrical
capacitance or resistance to measure
humidity changes.
Hygrometer
69. A dial hygrometer, in this case a hair
tension style. Note nonlinear scale.
Hygrometer
70. Metal/pulp coil type
The familiar metal/paper coil
hygrometer is useful for giving a dial
indication of humidity changes, but it
appears most often in very
inexpensive devices and their
accuracy is very limited.
Hair tension hygrometers
These devices use a human or animal
hair under tension
Types
73. Besides greenhouses and industrial
spaces, hygrometers are also used in some
incubators (egg), saunas, humidors and
museums. They are also used in the care of
wooden musical instruments such as
guitars and violins which can be damaged
by improper humidity conditions. In
residential settings, hygrometers are used
to aid humidity control (too low humidity
damages human skin and body, while too
high humidity favours growth of mildew and
dust mite).
Applications
74. Hygrometers are also used in the coating
industry because the application of paint
and other coatings may be very sensitive
to humidity and dew point. With a
growing demand on the amount of
measurements taken the psychrometer
is now replaced by a dewpoint gauge
known as a Dewcheck. These devices
make measurements a lot faster but are
often not allowed in explosive
environments.
Applications
75. The interior of a Stevenson screen
showing a motorized psychrometer
Psychrometers
76. A psychrometer consists of two
thermometers, one which is dry and one
which is kept moist with distilled water
on a sock or wick. The two
thermometers are thus called the dry-
bulb and the wet-bulb. At temperatures
above the freezing point of
water, evaporation of water from the
wick lowers the temperature, so that the
wet-bulb thermometer usually shows a
lower temperature than that of the dry-
bulb thermometer.
Psychrometers
77. When the air temperature is below freezing,
however, the wet-bulb is covered with a
thin coating of ice and may be warmer than
the dry bulb. Relative humidity is computed
from the ambient temperature as shown by
the dry-bulb thermometer and the
difference in temperatures as shown by the
wet-bulb and dry-bulb thermometers.
Relative humidity can also be determined by
locating the intersection of the wet- and
dry-bulb temperatures on a psychrometric
chart.
Psychrometers
79. Attempts of standardized
temperature measurement have been
reported as early as 170 AD by
Claudius Galenus. The modern
scientific field has its origins in the
works by Florentine scientists in the
17th century. Early devices to
measure temperature were called
thermoscopes.
Temperature measurement
80. The first sealed thermometer was
constructed in 1641 by the Grand Duke
of Toscani, Ferdinand II. The
development of today's thermometers
and temperature scales began in the
early 18th century, when Gabriel
Fahrenheit adapted a thermometer using
mercury and a scale both developed by
Ole Christensen Rømer. Fahrenheit's
scale is still in use, alongside the Celsius
scale and the Kelvin scale.
Temperature measurement
81. Many methods have been developed for
measuring temperature. Most of these
rely on measuring some physical
property of a working material that
varies with temperature. One of the
most common devices for measuring
temperature is the glass thermometer.
This consists of a glass tube filled with
mercury or some other liquid, which acts
as the working fluid.
Technologies
82. Temperature increase causes the fluid to
expand, so the temperature can be
determined by measuring the volume of
the fluid. Such thermometers are usually
calibrated so that one can read the
temperature simply by observing the
level of the fluid in the thermometer.
Another type of thermometer that is not
really used much in practice, but is
important from a theoretical
standpoint, is the gas thermometer.
Technologies
83. Thermistors
Resistance Temperature
Detector (RTD)
Pyrometer
Langmuir probes (for electron
temperature of a plasma)
Infrared
Other thermometers
Other important devices for
measuring temperature include:
