What is Thermal: Definition and 1000 Discussions

A thermal column (or thermal) is a column of rising air in the lower altitudes of Earth's atmosphere, a form of atmospheric updraft. Thermals are created by the uneven heating of Earth's surface from solar radiation, and are an example of convection, specifically atmospheric convection. The Sun warms the ground, which in turn warms the air directly above it. A thermal is a rising mass of buoyant air, a convective current in the atmosphere, that transfers heat energy vertically.

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  1. jisbon

    Thermal expansion (surface area)

    Hi all, For area expansion, I know the equation goes like: Hence, my answer to part i is ##\begin{aligned}A=A_{0}\left( 1+2\alpha \Delta T\right) \\ = 52\left( 1+2*24\times 10^{-6}\right) \left( 100\right) \\ =52.2496cm^{2}\end{aligned} ## Now I am unsure how to proceed with part 2 in this...
  2. carter7gindenv

    Clarification about Kirchhoff's law of thermal radiation

    Hello, I'd like some clarification with the exact wording of Kirchhoff's law of thermal radiation. The law states that at thermal equilibrium αλ=ελ. However sometimes I read that absorptivity= emissivity and sometimes I read that rate of A. = rate of E. Which one is correct? I'm not sure but I...
  3. Robert DeVries

    Trouble with fluid thermodynamics and nuclear thermal rockets

    Summary:: In need of help determining the exhaust velocity of a rocket nozzle given temperature and propellant molar mass Greetings and salutations! My name is Robert DeVries, world builder extraordinaire. I have come with questions in search of answers. So for the last few days I've been...
  4. FEAnalyst

    What are the causes of thermal stress?

    Hi, I would like to know what are all the possible causes of thermal stress. The most common are external constraints that block thermal expansion/contraction (for example a bar fixed at both ends). However I know that there are also at least two additional causes of thermal stress and that...
  5. carter7gindenv

    Thermal Radiation Behavior of Non-Black Bodies: I'm Confused!

    Hello, I've searched a bit about about the thermal radiation behavior of non-black body and I'm confused. I've read that the color is dependent only on the temperature so every thing display the same color as a black body. But at the same time I've read that materials don't always follow the...
  6. carter7gindenv

    Decoding Thermal Measurement Equations with KD2 Pro

    Hello, I'm working with a thermal property measurement tool (KD2 pro). The manual provide the equations used to measure temperature but I'm not sure that I understand them correctly. Temperature during heating (equation 1) T= m0 + m2t + m3 ln(t) Temperature during cooling (equation 2) T= m0 +...
  7. ib43

    Thermal physics problem -- Pressure and temperature of air in a refrigerator

    There is this one problem from past exam papers which I cannot seem to do: The air in a kitchen has pressure 1.0 x 10^5 Pa and temperature 22'C. A refrigerator of internal volume 0.36 m^3 is installed in the kitchen. (a) With the door open the air in the refrigerator is initially at the same...
  8. Demystifier

    A The ontology problem of thermal interpretation

    I have already discussed the ontology problem of thermal interpretation (TI) of quantum mechanics (QM) several times in the main thread on TI. The following is supposed to be the final refined version of my argument, so I don't want it to be lost among other posts in the main TI thread...
  9. NP04

    Linear Thermal Expansion with respect to time

    ΔL= αLoΔT ΔL = (23*10^-6)(0.2480 m)(28.30°C) ΔL = 1.61 * 10^-4 Period is 1s, so each second the pendulum moves 1.61 * 10^-4 m 1.61 * 10^-4 m/s *(60s/1min)*(60min/1hr)*(24hr/1day) = 13.95 m/day T = s (1:1 ratio) 13.95 seconds. But the answer is actually 69.3 s. Is the equation T = 2π√L/g...
  10. B

    Constant of thermal conductivity and heat flow in a given time

    Here is the Q below I want to see if my values for part b) is okay? This is what I have tried: Any help would be nice! Thanks
  11. J

    I Thermal photons emission inside a material

    in the inside of the material is heat also can transferred by radiation?
  12. J

    Thermal radiation in CMOS transistors

    Inside a CPU, when applying voltage to the gates of the CMOS transistor(high input), are the gate ore another components of a transistor will generate thermal radiation which will be absorbed by the neighboring transistor?
  13. Y

    Homework Help: Thermal Energy Question

    I don't know what to do!
  14. M

    Thermal coefficient of expansion for glycerin

    I am trying to find out where to get the Thermal coefficient of expansion for glycerin. The only thing I keep getting when using Google is mathematical examples that use glycerin as an example and its coefficient but I need to know where this number is coming from. Ex: 4.85 × 10^-4 (°C)-1
  15. K

    I Thermal interpretation and EPR experiment

    [Moderator's note: Thread spun off from previous thread due to topic change.] The thermal interpretation of the double slit experiment is very appealing alternative explanation to the Bohmian interpretation as I understood it from these discussions...
  16. E

    Engineering Input-referred thermal noise voltage (Razavi exercise)

    So this is a problem from the legendary Razavi book "Design of Analog CMOS Integrated Circuits" (Specifically, it is the problem 7.7 (c)). I got the solutions online but when I try to calculate the noise expression myself, I don't arrive at the same result. Lambda is assumed zero for neglecting...
  17. Z

    Accelerated Thermal Cycling: The Impact of Rate of Increase

    When ICs undergo accelerated testing via thermal cycling, wouldn't rate of temperature increase factor into the equation? For example, in Equation 4 in this pdf: http://www.issi.com/WW/pdf/semiconductor-reliability.pdf The Temp Cycling Acceleration Factor is a function of Tmax,stress and...
  18. EEristavi

    Thermal Expansion of a Liquid

    ##\Delta V = \beta V \Delta T####\rho _2 = \frac m {V + \Delta V} = \frac { \rho V} {V(1+\beta \Delta T)} = \frac \rho {1+\beta \Delta T}## ##\Delta \rho = \rho _2 - \rho = \frac \rho {1+\beta \Delta T} - \rho = \rho (\frac 1 {1+\beta \Delta T} - 1) = \rho \frac {-\beta \Delta T} {1+\beta \Delta...
  19. L

    Engineering How do I model a Thorium Reactor thermal system?

    Hi, I'm working on a project for a thermal fluids design class in which a theoretical Thorium reactor is to be designed and modeled, and I'm a little bit at a loss for how to start analyzing the problem. I know the system will have 4 fluid systems: an enriched FLiBe system connected via HX to...
  20. D

    Help with this formula for the Thermal Expansion of a pipe please

    I do not understand how this formula is derived: Can somebody help me? Source: https://www.corzan.com/en-us/piping-systems/specification/thermal-expansion
  21. carter7gindenv

    Thermal inertia vs effusivity, what is the difference?

    Hello, I'm slowly getting crazy about this stuff. I'm trying to understand what are thermal inertia/effusivity and information have been incoherent so far. The best example of that is seen on wikipedia where the only mention of thermal inertia is in the article...
  22. Anand Sivaram

    Thermal Imaging of people and background temperature

    Any object with a temperature emits corresponding EM waves. Thermal imaging works by considering our temperature of 37C/98.4F/310K, and it corresponds to 9.3um LWIR as per Wien's law. I was thinking about the following summer scenarios in which how it would work. 1) If...
  23. F

    How is absorbed thermal energy invested during a phase change?

    Hello, I was pondering on the well known fact that a certain amount of substance, when absorbing heat, increases in temperature up to a certain temperature and then phase (state) transformation takes place. Any energy supplied at that point does not increase the temperature any further but is...
  24. F

    Why is it more efficient to get thermal energy from a higher temperature source?

    Hello, Internal energy is the sum of the total KE and total PE of the system. Thermal energy is essentially representing the KE of the system and depends on temperature. When studying heat engines, we learn that it is better, in the name of efficiency, to get the same 1000 J of thermal energy...
  25. Izazo

    Overall Thermal Conductivity of Three different layers

    Overall thermal conductivity? for example, there are 3 layers made of different materials, having different thermal conductivities bonded with each other; conductivity of layer 1= k_1 = 1 W/m-K thickness of layer 1= t_1 = 0.004 m conductivity of layer 2= k_2 = 148 W/m-K thickness of layer 2=...
  26. N

    I Thermal interpretation and Bell's inequality

    Concerning p.198 of Bell's famous 1964 paper http://cds.cern.ch/record/111654/files/vol1p195-200_001.pdf How does TI explain Bell's move from the first equation to the second equation? Under TI, what is the physical significance of this move? Thank you.
  27. ValeForce46

    Two objects exchange heat through a cyclical thermal machine

    This is how I solved part a) : ##Q_1=C\cdot (T_1-T_i)## This quantity is negative because object 1 loses heat. (positive for the machine) ##Q_2=C\cdot (T_2-T_i)## This one is positive because the object 2 absorbs heat.(negative for the machine) Then the exchanged heat FOR THE MACHINE is...
  28. vanhees71

    A The thermal interpretation and measurement

    [Moderator's note: Spin off from previous thread since this is a separate topic from that one.] It's hard to expect that it ever gets a standard interpretation, because it contradicts the very observations which lead to the discovery of modern quantum including Born's probability interpretation...
  29. A

    Thermal Resistance of a Hollow Circular Cone

    We can write our radius as a function of the height, z, of our cone: $$R(z) = \frac{R_2 - R_1}{h} z + R_1$$ Where h is the height of our cone, ##h = \frac{L}{40}##. Our cross sectional area, $$A = 2 \pi R t$$ can then be written as $$A = 2 \pi t [\frac{R_2 - R_1}{h} z + R_1]$$ This I am all...
  30. K

    Thermal Expansion in Liquids and Steel

    This is a repost as I didn't read the community guidelines the first time. Hopefully this is better! First thing I did was write down both the linear and volume expansion formulas. I then multiplied my alpha by 3 and used the volume expansion equation for both materials. ∆V oil > ∆V pot, at the...
  31. K

    Thermal Expansion (liquid and solid) Question Help

    Summary: Help with volume and length expansion question Hi, I am struggling with this question. I understand that beta = 3 alpha so you use this to sub into the volume expansion equation. Is this correct? Can someone please provide a step by step instruction on how to do this question? Thank you !
  32. L

    Thermodynamic Systems - Power rating and thermal efficiency

    A coal fired steam plant takes in feed water at a temperature of 70°C and produces 15 tonnes of steam per hour at a pressure of 60 bar and temperature 400°C. The fuel consumption rate is 1.5 tonnes per hour and the calorific value of the fuel is 40MJkgˉ¹. Determine the power rating of the boiler...
  33. N

    I Confusion about the thermal interpretation's account of measurement

    I'm a mathematician with a longstanding interest in physics, and I've recently been enjoying reading and thinking about Arnold Neumaier's thermal interpretation, including some threads on this forum. There's something that's still confusing me, though, and I'm hoping someone here can clear it...
  34. T

    Heat capacity vs Thermal conductivity in a LN2 bath

    I worked on a lab experiment that was meant to measure heat capacity but left me with some other questions. The students measured the mass of a cup of liquid nitrogen as it boiled off, recording mass vs time. Then they drop a solid object into the bath, one experiment with a small bit iron...
  35. N

    Calculate the thermal diffusivity from minimal information

    So I started from the heat governing equation above. There is no heat generation or matter flow, so I simplified it to dT/dt = A d^(2)T/dx^(2). Now I assume dT/dt = (278.15K-277.38K)/(1200s-900s) = 0.0025667. But then I'm stuck with the d^(2)T/dx^(2). Is the x just 0.20 m? For T I used 288.15K...
  36. HumanistEngineer

    Mutual Thermal Resistances between Pipe Layers

    Ref: Palsson, Halldor | Analysis of Numerical Methods for Simulating Temperature Dynamics in District Heating Pipes - please check pg. 62 at LINK (CLICK!) INTRO: In this reference, the mutual thermal resistances between layers as water-insulation, ground-surrounding, and insulation-ground are...
  37. DaTario

    A Thermal State in Relativity Theory: Can It Happen?

    Hi All, Considering a set of many many small hard balls which start colliding inside a box. The velocities of these balls being mostly greater than c/2. Is it possible, in this case, to speak of convergence to a thermal state in the same sense of ordinary thermodynamics (i.e., using...
  38. J

    I Relational Hidden Variables (Real ensemble or thermal?)

    Smolin latest book about the quantum is quite interesting. Its called "Einstein Unfinished Revolution: Search for What Lies Beyond the Quantum" and he has a new theory or interpretation. Id like to know what you make of it. The theory is very simple. Similar views produce QM. May i know how this...
  39. NTL2009

    Electrical Please double-check my thermal dissipation assumptions

    BACKGROUND, skip if you want: I'm repairing the amps (2) and power supply for a 1970's era Rhodes Electric Piano (for my local HS music depart). Since this is a classic instrument, I found plenty of info, so the rebuild went well, but I'm curious about one thing, and want to check my...
  40. I

    I What Determines the Maximum Number of Microstates at Equilibrium?

    ## \Omega(E_1)## is the number of microstates accessible to a system when it has an energy ##E_1## and ##\Omega(E_2)## is the number of microstates accessible to the system when it has an energy ##E_2##. I understand that each microstate has equal probability of being occupied, but could...
  41. A. Neumaier

    I More on the thermal interpretation

    I just finished a 4th part of my series of papers on the thermal interpretation: Foundations of quantum physics IV. More on the thermal interpretation This paper continues the discussion of the thermal interpretation of quantum physics. While Part II and Part III of this series of papers...
  42. A. Neumaier

    I Spectra in the thermal interpretation

    In any quantum system, the differences of the energy levels (the eigenvalues of the Hamiltonian ##H##) are in principle directly observable, since they represent excitable oscillation frequencies of the system and thus can be probed by coupling the system to a harmonic oscillator with adjustable...
  43. A. Neumaier

    I The double slit in the thermal interpretation

    I prefer to discuss in the double-slit experiment light in place of electrons since it makes the underlying principle more clear. Consider the quantum system consisting of the screen and an external (classical) electromagnetic field. This a very good approximation to many experiments, in...
  44. Demystifier

    A Schrodinger's Cat and the thermal interpretation

    [Moderator's note: spin-off from a previous thread since this discussion is a separate topic.] In this sense, the Schrodinger's famous thought experiment prepares the cat in a superposition of dead and alive. I still don't see how TI can possibly prevent it.
  45. Demystifier

    A Proof that the thermal interpretation of QM is wrong

    Preface After a lengthy discussion of the thermal interpretation of quantum physics in https://www.physicsforums.com/threads/the-thermal-interpretation-of-quantum-physics.967116/ , now I think I can prove that it is wrong, i.e. that it doesn't solve the measurement problem in a way it claims it...
  46. A

    Enhancing the thermal conductivity of Phase changing materials

    A) What are the modern techniques used for enhancing the thermal conductivity of Phase changing materials (PCM) ? B) what are the negative effects (disadvantages) of using old methods of enhancing thermal conductivity of PCM ? ( construct table ) C) what are the different techniques used for...
  47. PeterDonis

    A How does the thermal interpretation explain Stern-Gerlach?

    I am posting this question separately from the ongoing thermal interpretation thread started by @A. Neumaier since it is a question about a specific experiment and how that interpretation explains it. The experiment is the Stern-Gerlach experiment. For concreteness, I will specify that we are...
  48. Clara Chung

    Question about a thermal cycle

    Attempt: a) Leg 4 and Leg 1 W=P_0(V_1-V_0)+P_1(V_0-V_1) b) Leg 4: Q= C_v*ΔT=C_v*ΔP*V_0/nR = 3/2*(V_0*P_0-V_0*P_1) Leg 1: Q=C_p*ΔT=C_p*P_0*ΔV/nR = 5/2*(P_0*V_1-P_0*V_0) Q=3/2*(V_0*P_0-V_0*P_1)+ 5/2*(P_0*V_1-P_0*V_0) c) W/Q = [P_0(V_1-V_0)+P_1(V_0-V_1)] / [3/2*(V_0*P_0-V_0*P_1)+...
  49. T

    Thermal balance in calorimeter after adding lead

    Since ΔT is change in temperature, the container and it's contents and the led most have same temperature difference when the led is added. I tried by assuming that energy released by the led is same as the amount that container and it's contents absorb. Meaning Q1-Q2 = 0 => Q1 = Q2. $$ \Delta...
  50. dRic2

    Can Anisotropic Materials Have Asymmetric Thermal Conductivity Tensors?

    Hi, yesterday a professor of mine told me that if you have a temperature gradient along the x-axsis you could have heat flowing in the y direction. Mathematically it is pretty straightforward to find the thermal conductivity tensor required, but in real life can you name some materials that...
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