question: Why can we feel hot/sweaty, but when you touch your skin (or someone else does) the skin feels cold?
comment: Because sweating is your bodies natural cooling mechanism. The moisture is evaporated away taking heat with it. This is more evident at the surface of the skin, hence it feeling cooler.
passages: According to the laws of thermodynamics, all particles of matter are in constant random motion as long as the temperature is above absolute zero. Thus the molecules and atoms which make up the human body are vibrating, colliding, and moving. This motion can be detected as temperature; higher temperatures, which represent greater kinetic energy in the particles, feel warm to humans who sense the thermal energy transferring from the object being touched to their nerves. Similarly, when lower temperature objects are touched, the senses perceive the transfer of heat away from the body as feeling cold.
   Blood circulation transports heat throughout the body, and adjustments to this flow are an important part of thermoregulation. Increasing blood flow to the surface (e.g., during warm weather or strenuous exercise) causes warmer skin, resulting in faster heat loss. In contrast, when the external temperature is low, blood flow to the extremities and surface of the skin is reduced and to prevent heat loss and is circulated to the important organs of the body, preferentially.
  
  Section::::Physiology.:Rate of blood flow.
   Section::::Heat transfer.
  
  Section::::Heat transfer.:Heat transfer between two bodies.
  
  Referring to conduction, Partington writes: "If a hot body is brought in conducting contact with a cold body, the temperature of the hot body falls and that of the cold body rises, and it is said that a "quantity of heat" has passed from the hot body to the cold body."
  
  Referring to radiation, Maxwell writes: "In Radiation, the hotter body loses heat, and the colder body receives heat by means of a process occurring in some intervening medium which does not itself thereby become hot."
   Thermoception
  
  Thermoception or thermoreception is the sense by which an organism perceives temperature, or more accurately, temperature differences inferred from heat flux. The details of how temperature receptors work are still being investigated. Ciliopathy is associated with decreased ability to sense heat, thus cilia may aid in the process. Transient receptor potential channels (TRP channels) are believed to play a role in many species in sensation of hot, cold, and pain. Vertebrates have at least two types of sensor: those that detect heat and those that detect cold.
   BULLET::::2. : contains a variety of nerve endings that jump to heat and cold, touch, pressure, vibration, and tissue injury (see somatosensory system and haptic perception).
  
  BULLET::::3. Thermoregulation: eccrine (sweat) glands and dilated blood vessels (increased superficial perfusion) aid heat loss, while constricted vessels greatly reduce cutaneous blood flow and conserve heat. Erector pili muscles in mammals adjust the angle of hair shafts to change the degree of insulation provided by hair or fur.
  
  BULLET::::4. Control of evaporation: the skin provides a relatively dry and semi-impermeable barrier to reduce fluid loss.
   The cutaneous somatosensory system detects changes in temperature. The perception begins when thermal stimuli from a homeostatic set-point excite temperature specific sensory nerves in the skin. Then with the help of sensing range, specific thermosensory fibers respond to warmth and to cold. Then specific cutaneous cold and warm receptors conduct units that exhibit a discharge at constant skin temperature.
  
  Section::::Temperature modality.:Nerve fibers for temperature.
   Thermoception is the sense of heat and the absence of heat (cold) by the skin and internal skin passages, or, rather, the heat flux (the rate of heat flow) in these areas. There are specialized receptors for cold (declining temperature) and for heat (increasing temperature). The cold receptors play an important part in the animal's sense of smell, telling wind direction. The heat receptors are sensitive to infrared radiation and can occur in specialized organs, for instance in pit vipers. The thermoceptors in the skin are quite different from the homeostatic thermoceptors in the brain (hypothalamus), which provide feedback on internal body temperature.
   One may observe that the heat flow is directly related to the thermal conductivities of the bodies in contact, formula_6 and formula_7, the contact area formula_4, and the thermal contact resistance, formula_9, which, as previously noted, is the inverse of the thermal conductance coefficient, formula_1.
  
  Section::::Importance.
  
  Most experimentally determined values of the thermal contact resistance fall between
  
  0.000005 and 0.0005 m² K/W (the corresponding range of thermal contact
   Heat transfer by convection is driven by the movement of fluids over the surface of the body. This convective fluid can be either a liquid or a gas. For heat transfer from the outer surface of the body, the convection mechanism is dependent on the surface area of the body, the velocity of the air, and the temperature gradient between the surface of the skin and the ambient air. The normal temperature of the body is approximately 37 °C. Heat transfer occurs more readily when the temperature of the surroundings is significantly less than the normal body temperature. This concept explains why a person feels cold when not enough covering is worn when exposed to a cold environment. Clothing can be considered an insulator which provides thermal resistance to heat flow over the covered portion of the body. This thermal resistance causes the temperature on the surface of the clothing to be less than the temperature on the surface of the skin. This smaller temperature gradient between the surface temperature and the ambient temperature will cause a lower rate of heat transfer than if the skin were not covered.
   Warm and cold sensitive nerve fibers differ in structure and function. The cold-sensitive and warm-sensitive nerve fibers are underneath the skin surface. Terminals of each temperature-sensitive fiber do not branch away to different organs in the body. They form a small sensitive point which are unique from neighboring fibers. Skin used by the single receptor ending of a temperature-sensitive nerve fiber is small. There are 20 cold points per square centimeter in the lips, 4 in the finger, and less than 1 cold point per square centimeter in trunk areas. There are 5 times as many cold sensitive points as warm sensitive points.
   Skin wettedness is defined as "the proportion of the total skin surface area of the body covered with sweat."
   BULLET::::- Arteriolar vasodilation occurs. The smooth muscle walls of the arterioles relax allowing increased blood flow through the artery. This redirects blood into the superficial capillaries in the skin increasing heat loss by convection and conduction.
  
  Section::::In hot and humid conditions.
   BULLET::::- Your body is your private property. No one else has the right to touch it. (When you were really young, maybe members of your family, like your mom, dad, grandma, grandpa, aunt, or uncle needed to touch your body when they helped you in the bathtub or changed your diaper as you were too young to do it by yourself. Also, doctors need to touch your body to keep you healthy, because they are in the body business.)
   The somatosensory system includes multiple types of sensations from the body. This includes light, touch, pain, pressure, temperature, and joint /muscle sense. Each of these are categorized in three different areas: discriminative touch, pain and temperature, and proprioception. Discriminative touch includes touch, pressure, being able to recognize vibrations, etc. Pain and temperature includes the perception of pain/ amounts of pain and the severity of temperatures. The pain and temperature category of sensations also includes itching and tickling. Proprioception includes receptors for everything that occurs below the surface of the skin. This includes sensations on various muscles, joints, and tendons. Each of these three categories have their own types of pathways and receptors. These pathways target the cerebellum in the brain. This section of the brain tracks what the muscles are doing at all times so any potential damage to this area can greatly affect one's senses.
   Section::::Influencing factors.:Relative humidity.:Interplay of temperature and humidity.
  
  Various types of apparent temperature have been developed to combine air temperature and air humidity. 
  
  For higher temperatures, there are quantitative scales, such as the heat index.
  
  For lower temperatures, a related interplay was identified only qualitatively:
  
  High humidity and low temperatures cause the air to feel chilly.
  
  Cold air with high relative humidity "feels" colder than dry air of the same temperature because high humidity in cold weather increases the conduction of heat from the body.
   BULLET::::- Steinar Gundersen (also known as "Azarak") – lead guitars
  
  BULLET::::- A.O. Grønbech (Obsidian Claw) – rhythm guitars
  
  BULLET::::- Lars K. Norberg – bass
  
  BULLET::::- Jonna Nikula – keyboards
  
  Section::::Credits.:Session.
  
  BULLET::::- Victor Brandt – bass (on "My Skin is Cold")
  
  BULLET::::- Snorre Ruch – additional guitars (on "My Skin is Cold")
  
  BULLET::::- Knut "Euroboy" Schreiner – guitar solo (on "Existential Fear-Questions")
  
  Section::::Production.
  
  BULLET::::- Engineered by Lars Klokkerhaug at Sonic Society, April 2008
  
  BULLET::::- Mixed by Lars Klokkerhaug and Satyr at Sonic Society, April 2008
  
  Section::::Trivia.
   It differs from other forms of electromagnetic radiation such as x-rays, gamma rays, microwaves, radio waves, and television rays that are not related to temperature. Scientists have found that all bodies at a temperature above absolute zero emit thermal radiation. People are constantly radiating their body heat, but at different rates. From these values, the rate of heat loss from a person is almost four times as large in the winter than in the summer, which explains the “chill” we feel in the winter even if the thermostat setting is kept the same.
   The “radiation effect” results from radiation heat exchange between human bodies and surrounding surfaces, such as walls and ceilings. It may lead to phenomena such as houses feeling cooler in the winter and warmer in the summer at the same temperature. For example, in a room in which air temperature is maintained at 22° Celsius at all times, but in which the inner surfaces of the house is estimated to be an average temperature of 10° Celsius in the winter or 25° Celsius in the summer, heat transfer from the surfaces to the individual will occur, resulting in a difference in the perceived temperature.
   There has been controversy over why damp cold air feels colder than dry cold air. Some believe it is because when the humidity is high, our skin and clothing become moist and are better conductors of heat, so there is more cooling by conduction.
  
  Section::::Influencing factors.:Natural ventilation.
   When the two bodies come in contact, surface deformation may occur on both bodies. This deformation may either be plastic or elastic, depending on the material properties and the contact pressure. When a surface undergoes plastic deformation, contact resistance is lowered, since the deformation causes the actual contact area to increase
  
  Section::::Factors influencing contact conductance.:Surface cleanliness.
  
  The presence of dust particles, acids, etc., can also influence the contact conductance.
  
  Section::::Measurement of thermal contact conductance.
   A body force is distinct from a contact force in that the force does not require contact for transmission. Thus, common forces associated with pressure gradients and conductive and convective heat transmission are not body forces as they require contact between systems to exist. Radiation heat transfer, on the other hand, is a perfect example of a body force.
  
  More examples of common body forces include;
  
  BULLET::::- Gravity,
  
  BULLET::::- Electric forces acting on an object charged throughout its volume,
  
  BULLET::::- Magnetic forces acting on currents within an object, such as the braking force that results from eddy currents,
   Thermal comfort as a "condition of mind" is "defined" in psychological terms. Among the factors that affect the condition of mind (in the laboratory) are a sense of control over the temperature, knowledge of the temperature and the appearance of the (test) environment. A thermal test chamber that appeared residential "felt" warmer than one which looked like the inside of a refrigerator.
  
  Section::::Models.:Adaptive comfort model.:Physiological Adaptation.
   Pathways for touch-position and pain-temperature sensations from the face and body merge in the brainstem, and touch-position and pain-temperature sensory maps of the entire body are projected onto the thalamus. From the thalamus, touch-position and pain-temperature information is projected onto the cerebral cortex.
  
  Section::::Function.:Summary.
  
  The complex processing of pain-temperature information in the thalamus and cerebral cortex (as opposed to the relatively simple, straightforward processing of touch-position information) reflects a phylogenetically older, more primitive sensory system. The detailed information received from peripheral touch-position receptors is superimposed on a background of awareness, memory and emotions partially set by peripheral pain-temperature receptors.
   Somatosensory sensations occur when receptors detect changes on one's skin or within one's body.
  
  Section::::Types of sensations.:Somatosensory.:Cutaneous sensations.
  
  Sensations on the skin are detected by cutaneous receptors. These receptors may feel sensations such as pain, tickle, cold, hot, soft, and rough. Mechanoreceptors detect light pressure (e.g., caress), vibration, and texture, nociceptors detect strong pressure (e.g., pain), and thermoreceptors detect temperature.
   Thermoreceptors are sensory receptors, which respond to varying [temperature]s. While the mechanisms through which these receptors operate is unclear, recent discoveries have shown that mammals have at least two distinct types of thermoreceptors.
  
  The bulboid corpuscle, is a cutaneous receptor a "cold-sensitive" receptor, that detects cold temperatures. The other type is a warmth-sensitive receptor.
  
  Section::::Types and function.:External.:Mechanoreceptors.
  
  Mechanoreceptors are sensory receptors which respond to mechanical forces, such as pressure or distortion.
  