B
Bluetongue1
Guest
I wrote a response to a discussion about this but unfortunately the thread was locked in the meantime. As an understanding of the difference between these concepts is of value to the herp hobbyist, I feel it is still worth posting…
So what is heat? It is actually the amount movement energy of the particles of matter. When you take the temperature of a substance you are measuring the average movement energy of the particles.
What then is Infrared (IR)? IR is a form of radiation – electromagnetic radiation (EMR) to be precise. This consists of alternating magnetic and electric fields, in a wave pattern, at right angles to each other. The electric field produces a magnetic field. The magnetic field then produces an electric field in the opposite direction. This electric field produce a magnetic field opposite to the original…. and so. It is said to be self-propagating.
Given the wave shaped fields of EMR, they have a given and constant wavelength. The properties of the radiation are determined by that wave length. From longest to shortest… Electric Power, TV waves, Radio waves, Microwave, Light, X rays, Gamma Rays, Cosmic Rays.
The Light section of the spectrum has certain physical properties in common and varying individual properties according to the particular wavelength. Light is split into 3 main sections, each based on their general properties… Infrared Radiation, Visible Light, Ultraviolet Light.
So what are the properties of radiation in the IR part of the spectrum? IR is not visible to the eyes. When IR is absorbed by matter, it causes the particles that absorb it to speed up. In other words, it increases the heat of that which is absorbing it. IR is not absorbed by air – it passes straight through it. If you have been at the beach and standing in the sun, you would have felt the heat developing in your skin. Step into the shade and all of a sudden you are cool. The air is not being heated only your skin. For the same reason the sand can be burning while the air is cool.
How does this apply to snakes?
The first issue is use of the term “see” whereit does not apply. This is not equivalent to the term “perceive”. Any receptor can perceive a stimulus it is designed to detect. Seeing is confined to where light produces an image an of some form which is then percieved by muliple receptors. This is then sent to the 'brain' where it is interpreted as a 'map' of what can be sensed. The existence of one or more lenses to focus the image is a good indicator as to whether you would classify the perception of the stimuli as sight.
The second issue is the misuse of the term “heat receptors” or “heat sensing pits”. This is technically incorrect. Pythons (and other snakes) do NOT detect “heat” – they detect IR radiation. The IR detected is not focussed into an image so it is appropriate to say they ‘perceive it’ but not to say they ‘see it’.
Objects that are hotter than their surrounding, will continually convert a percentage of their heat into IR radiation. This is part of the cooling down process until they reach the point where their temperature is equivalent to that of their surroundings. The higher the difference to the surrounding temperatures, the greater the amount of IR produced. The rate at which hot objects radiate IR is also related to their colour. For example, black objects radiate more IR than white objects at the same temperature.
Incandescent globes produce a much higher amount of IR than they do visible light. They are only around around 12% effficient at converting the energy going into them intovisible light. The remaining energy causes the globe to heat up, which will be given off as transferred heat or IR. Party globes are simply painted incandescent globes designed to restrict the wavelengths emitted. Ceramic heat emitters produce no visible light but only IR.
Blue
Any questions or queries?
So what is heat? It is actually the amount movement energy of the particles of matter. When you take the temperature of a substance you are measuring the average movement energy of the particles.
What then is Infrared (IR)? IR is a form of radiation – electromagnetic radiation (EMR) to be precise. This consists of alternating magnetic and electric fields, in a wave pattern, at right angles to each other. The electric field produces a magnetic field. The magnetic field then produces an electric field in the opposite direction. This electric field produce a magnetic field opposite to the original…. and so. It is said to be self-propagating.
Given the wave shaped fields of EMR, they have a given and constant wavelength. The properties of the radiation are determined by that wave length. From longest to shortest… Electric Power, TV waves, Radio waves, Microwave, Light, X rays, Gamma Rays, Cosmic Rays.
The Light section of the spectrum has certain physical properties in common and varying individual properties according to the particular wavelength. Light is split into 3 main sections, each based on their general properties… Infrared Radiation, Visible Light, Ultraviolet Light.
So what are the properties of radiation in the IR part of the spectrum? IR is not visible to the eyes. When IR is absorbed by matter, it causes the particles that absorb it to speed up. In other words, it increases the heat of that which is absorbing it. IR is not absorbed by air – it passes straight through it. If you have been at the beach and standing in the sun, you would have felt the heat developing in your skin. Step into the shade and all of a sudden you are cool. The air is not being heated only your skin. For the same reason the sand can be burning while the air is cool.
How does this apply to snakes?
The first issue is use of the term “see” whereit does not apply. This is not equivalent to the term “perceive”. Any receptor can perceive a stimulus it is designed to detect. Seeing is confined to where light produces an image an of some form which is then percieved by muliple receptors. This is then sent to the 'brain' where it is interpreted as a 'map' of what can be sensed. The existence of one or more lenses to focus the image is a good indicator as to whether you would classify the perception of the stimuli as sight.
The second issue is the misuse of the term “heat receptors” or “heat sensing pits”. This is technically incorrect. Pythons (and other snakes) do NOT detect “heat” – they detect IR radiation. The IR detected is not focussed into an image so it is appropriate to say they ‘perceive it’ but not to say they ‘see it’.
Objects that are hotter than their surrounding, will continually convert a percentage of their heat into IR radiation. This is part of the cooling down process until they reach the point where their temperature is equivalent to that of their surroundings. The higher the difference to the surrounding temperatures, the greater the amount of IR produced. The rate at which hot objects radiate IR is also related to their colour. For example, black objects radiate more IR than white objects at the same temperature.
Incandescent globes produce a much higher amount of IR than they do visible light. They are only around around 12% effficient at converting the energy going into them intovisible light. The remaining energy causes the globe to heat up, which will be given off as transferred heat or IR. Party globes are simply painted incandescent globes designed to restrict the wavelengths emitted. Ceramic heat emitters produce no visible light but only IR.
Blue
Any questions or queries?
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) who this may be news to i think someone owes ZANKS an apology although i dont think we will ever get it
