Add class 'radiation'

[stap-m]

Description of the issue

From the 6th oeo developer meeting.

Find classification for radiation ("It is not a subclass of energy, but what would the respective subclass of energy be called?") and definition.

Related to #224 and solar issues

Ideas of solution

Workflow checklist

• [ ] I discussed the issue with someone else than me before working on a solution
• [ ] I already read the latest version of the workflow for this repository
• [ ] I added this issue to the Project 'Issues'. If suitable, I add it to further Projects.
• [ ] The goal of this ontology is clear to me

I am aware that

• [ ] every entry in the ontology should have a definition
• [ ] classes should arise from concepts rather than from words

[l-emele]

Is it an energy transfer?

[akleinau]

Is it an energy transfer?

I'm not sure if radiation is the process of sending out waves which could fit with energy transfer or the waves itself. Waves again aren't really objects (no clear border) or object aggregates (no distinction into objects). "a wave is a disturbance (change from equilibrium) of one or more fields" says wikipedia which is even more confusing because what is a disturbance in our BFO-world?

[akleinau]

The problem with "energy transfer" is that radiation then has to have some type of energy as output but the output is primarily called a wave. A wave can be a high-energy wave but it's not energy itself?

[l-emele]

Okay, it seems we're approaching complications of the the quantum world and I am not a physicist. 😄

The wave is the "vehicle" to transport the energy, e.g from the sun to earth. The process of using a wave to transport energy/information/etc is called radiation. Due to the wave-particle duality the wave is at the same time a stream of small energy particles (photons) from the sun to earth.

[carstenhoyerklick]

Hi everybody,

in the first place we should use different terms. Radiation is a commenly used term, but not quite correct in meteorology. There we use either irradiation or irradiance. They are two different things, which frequently get mixed up, as the numbers are the same for hourly values on a square meter.

• Irradiance is an instantaneous value and describes a power (Leistung) of solar rays on a defined area. The unit is usualy W/m².
• Irradiation is an enery, so power integrated over time. The unit are Wh/m². Irradiation defenitely needs a time step (see #267) over which it has been recorded.

Unfortunately, if you have an irradiance of 500W/m², it results into an irradiation of 500Wh/m², if you look at hourly values or average irradiations if they are converted into Wh/m². That is why these terms tend to get mixed up.

[l-emele]

in the first place we should use different terms.

What term would you then use to describe the process itself? Irradiance and irradiation according to your descriptions are power resp. energy densities but not processes.

[akleinau]

@carstenhoyerklick So irradiance and irradiation can be described as a value with a unit, therefore a quantity value? radiation still looks to me like the most known term for the process of emitting radiant energy. @l-emele do you know an example where we need the process, not the quantity values?

[stap-m]

Are irradiance / irradiatiation mainly used in meteorology, i.e. should we refer to "solar" in the definition? @carstenhoyerklick

I think, we need concepts for all three terms: radiation, irradiance, irradiatiation: In issue #522 we're discussing energy subclasses and in the def of energy we are referring to "ratiation". Thus, we should define this term, too, the sooner the better, so that we can proceed with the other issue. (Or else, change the def of energy :eyes:)

In source radiation sounds like a process. I slightly adjusted it: radiation is the emission or transmission of energy in the form of waves or particles through a spatial region or a material entity. The problem with this def is, that it referres to energy itself...

[l-emele]

In source radiation sounds like a process. I slightly adjusted it: radiation is the emission or transmission of energy in the form of waves or particles through a spatial region or a material entity. The problem with this def is, that it referres to energy itself...

I see the problem, but the solution might be to define solar energy as the output of this energy transport process. The input of this process would be the nuclear energy of the sun. Btw, we did not yet define an energy transport process, did we? Shall I open an issue for that?

[stap-m]

I see the problem, but the solution might be to define solar energy as the output of this energy transport process. The input of this process would be the nuclear energy of the sun

At least for #522 we need a generic def of radiation. Other "things" can emit radiation, too.

[l-emele]

Just discussed bilaterally with @stap-m:

• radiation is a direct subclass of process and we agree to the definition proposal above.
• We define a subclass solar radiation which has output solar energy. So the solar energy is then the energy arriving (e.g.) on Earth.
• We generally agree to irradiance and irradiation being power resp. energy densities. I'll open a separate issue for that.

That leaves for this issue here only radiation and solar radiation. I agree with the definition of radiation from @stap-m. Maybe we can improve it a little bit to make it Aristotelian?

[stap-m]

Radiation is the process of emitting or transmitting energy in the form of waves or particles through a spatial region or a material entity. ?

[l-emele]

Radiation is the process of emitting or transmitting energy in the form of waves or particles through a spatial region or a material entity. ?

I agree. And from that: Solar radiation is radiation that is emitted by the sun?