Recent content by jones123

  1. J

    I Calculating the incidence angle of the Sun

    Hi all, I have some difficulties understanding a formula for calculating the incidence angle for incoming solar radiation on a sloping surface. I found that: angle of incidence calculated as cos(j) = sin((pi/2)-surface slope)*sin(altitude angle) + cos((pi/2)-surface slope)*cos(altitude...
  2. J

    Unit conversion meters Newtons years seconds

    Hi, I need to convert a value of 12*10-16 m7 N-3 y-1 to the units of kPa-3 m2 s-1. Can anyone help me? where: m = meters, N = Newton, y = year, s = seconds. Thanks!
  3. J

    I Calculation of daily solar insolation

    Hi, calculations were based on Part 4: Irradiation Calculations | ITACA:
  4. J

    I Calculation of daily solar insolation

    Hi all, I'm trying to calculate the daily solar insolation (integrated solar irradiances from sunrise to sunset) for a given location and day of the year. For latitude 43.2° and April 15th, I get: H0 = (solar constant * scale factor for intra annual variation of sun-earth distance * 86400...
  5. J

    I Calculation of the hour angle of the Sun

    Hi all, According to the sunrise equation, the hour angle of the sun at sunset is: cos H = -tan(a)tan(d) where H = the hour angle, a = latitude and d = solar declination angle. This equation says that H at sunset = -H at sunrise. Now, I have a few questions concerning that: 1) I was...
  6. J

    Brightness temperature in remote sensing

    Hi all, I don't know if I'm on the right forum to ask this, but maybe somebody knows anything about brightness temperatures measured by remote sensing devices. In a paper that I read "Atmospheric corrections for retrieving ground brightness temperature at commonly-used passive microwave...
  7. J

    Temperature change (first law of thermodynamics)

    Oh I get it, it's just that the temperature change is Eulerian (a local change at a fixed position) whereas the energy flux density is Lagrangian (it crosses the air on its path while having a negative or positive value).
  8. J

    Temperature change (first law of thermodynamics)

    Hi, From the first law of thermodynamics it follows: Cp * (δT/δt) = (δQ/δt) where Cp = specific heat capacity, T = temperature, Q = heat, t = time From this formula, you would derive that temperature keeps on increasing as long as dQ/dt > 0. But if you, for example, look at the idealized...
  9. J

    Exercise on collisions and oscillations

    Hi, I tried to solve this problem myself and I'd like someone to check it :) Thanks already! A ball is rolling towards a block, which is connected to a spring. Assume no friction occurs. The initial velocity of the ball is 10 m/s. The spring constant is k = 5 N/m. Mass of the ball = 5 kg and...
  10. J

    Exercise on lenses (optics)

    Homework Statement An object is placed at 25 cm to the left of a diverging lens. A converging lens with a focal length of 12 cm is located 30 cm to the right of the diverging lens. The two-lenses-system forms a real inverted image 17 cm to the right of the converging lens (see attachment)...
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