Principles of Environmental Physics: Plants, Animals, and the Atmosphere 4 by John Monteith, Mike Unsworth | 9780123869937 | 0123869935 | Holooly

Principles of Environmental Physics: Plants, Animals, and the Atmosphere

53 SOLVED PROBLEMS

Question: 5.3

Using the results of Question 2, estimate the daily insolation at 45°N at solar noon on 21 June for the three aerosol loadings assuming cloudless sky. ...

Verified Answer:

The daylength n = 24

π^{−1}

c...

Question: 5.2

Use the simple model for solar radiation under cloudless skies (p. 64) to estimate the direct, diffuse, and total solar irradiance on a horizontal surface at 45°N at local solar noon on 21 June for three values of aerosol optical thickness, 0.05, 0.20, 0.40. Assume that the optical thickness for ...

Verified Answer:

At solar noon

\psi =\phi -\delta =45.0-23....

Question: 12.4

Calculate the fraction of an aerosol of 10 µm diameter particles that would be washed out of the atmosphere in 1 h by rainfall of 1 mm h^−1, assuming that the raindrops are all of the same radius, namely (i) 100 µm and (ii) 1000 µm. (Hints: Use Figure 12.1 or the method in Problem 1 to calculate ...

Verified Answer:

(This problem and solution were written by Dr. A.C...

Question: 8.5

Consider a sparse forest canopy with the following characteristics: Leaf area index L = 1.0. Theoretical attenuation coefficient Kb = 1.0 (assuming black leaves). Soil reflection coefficient ρs = 0.15. Leaf reflection coefficient (PAR) ρp = 0.10. Leaf transmission coefficient (PAR) τp = 0.10. ...

Verified Answer:

a.

\alpha _{p} = 1- \tau _{p} -\rho _{p} [...

Question: 9.1

Lycopodium spores with diameter 4.2 µm have a sedimentation velocity in air of 0.50 mm s^−1. Estimate their drag coefficient. ...

Verified Answer:

As

Re_{p}

is small (

Re_{p...

Question: 10.2

A silk worm, diameter 4 mm, is suspended vertically on a thread in a sunfleck in a plant canopy where the windspeed is 0.1 m s^−1. If the caterpillar’s temperature is 5 °C greater than the air temperature, estimate its rate of convective heat loss. ...

Verified Answer:

Re= 8\times 10^{-3} \times 0.05/15\times 1...

Question: 10.1

Estimate the Nusselt number for a flat plate with characteristic dimension 50 mm exposed to a windspeed of 2.0 m s^−1. Assume now that a real leaf can be treated as a flat plate with the same characteristic dimension, but that its Nusselt number is twice the value calculated earlier (i.e. β = 2, ...

Verified Answer:

For the flat plate,

Re= 2.0 \times 50\time...

Question: 12.1

Find the sedimentation velocities of (i) a pollen grain, diameter 10 µm, density 0.8 g cm^−3, and (ii) a hailstone, diameter 6 mm, density 0.5 g cm^−3. (Hint: You will have to estimate the Reynolds number and decide whether to use the trial-and-error method described in the text). ...

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i. If the pollen grain obeys Stokes’ Law, then [la...

Question: 12.2

Find the relaxation times and stopping distances of spores of 10 µm radius and aerosol particles of 0.5 µm radius in a gas moving at 2 m s^−1. Hence confirm that the spores would be deposited rapidly to the walls of a bronchus 4 mm diameter while the aerosol would penetrate effectively along the ...

Verified Answer:

\tau = m/6\pi \nu \rho _{a} r=2r^{2} \rho_...

Question: 13.6

A marathon runner, treated as a cylinder with diameter 33 cm moving at 19 km h^−1 relative to the surrounding air, has a net radiation load of 300 W m^−2. The air temperature and vapor pressure are 30 °C and 2.40 kPa, respectively. Assuming that the runner’s skin is covered with sweat that is a ...

Verified Answer:

The runner’s velocity, 19 km

h^{−1}

...

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