empirical constants in [Best 1950] drop spectrum (eq. 2.24) | ||||||

[m] | area | |||||

[m] | catchment area | |||||

empirical constant in [Best 1950] drop spectrum (eq. 2.24) | ||||||

slope of the fit function , in correlation plots | ||||||

[-] | mean pressure coefficient | |||||

empirical constant in [Best 1950] drop spectrum (eq. 2.24) | ||||||

, , , | parameters in a general formula for raindrop spectra (eq. 2.25) | |||||

[-] | drag coefficient | |||||

[-] | - model constant | |||||

[-] | - model constant | |||||

[-] | - model constant | |||||

[m] | displacement height | |||||

[m] | raindrop diameter | |||||

[m] | median median drop size (eq. 2.20) | |||||

[-] | roughness parameter (eq. 6.5) | |||||

[-] | fraction of liquid water in the air comprised by drops with diameters less than (eq. 2.19) | |||||

[m s] | gravitational acceleration | |||||

[m] | internal boundary layer height | |||||

[m] | building height; obstacle height | |||||

[-] | turbulence intensities | |||||

[-] | driving rain ratio (eq. 2.28) | |||||

[-] | von Kármán constant (0.4) | |||||

[m s] | turbulent kinetic energy per unit of mass | |||||

[m] | stopping distance | |||||

[m] | characteristic eddy dimension (section 2.2.3) | |||||

[m] | smaller of (two times building height) and (building width), section 2.1.4 | |||||

[m] | integral length scale | |||||

[kg] | mass | |||||

[kg m m] | raindrop mass concentration spectrum | |||||

[m m] | raindrop number concentration spectrum | |||||

[m m] | parameter in [Marshall and Palmer 1948] drop spectrum (eq. 2.21) | |||||

[-] | number | |||||

empirical constant in [Best 1950] drop spectrum (eq. 2.24) | ||||||

correlation coefficient; the coefficient of determination is (eq. 3.4) | ||||||

[mm h] | rain intensity, also expressed in [kg m s] = [mm s] | |||||

[mm h] | driving rain intensity | |||||

[-] | Reynolds number | |||||

[s] | time | |||||

[s] | averaging and summation period, the periods are synchronised to clock and calendar; the first period of a day starts at 00h00. | |||||

[s] | pause between rain spells | |||||

[s] | sample time | |||||

[s] | precipitation time | |||||

[s] | integral time (eq. 6.7) | |||||

[m s] | friction shear velocity | |||||

[m s] | wind velocity vector | |||||

[m s] | longitudinal, lateral and vertical wind velocity | |||||

[m s] | raindrop velocity vector | |||||

[m s] | raindrop velocity in , and direction | |||||

[m s] | wind speed | |||||

[m s] | horizontal wind speed | |||||

[m s] | horizontal wind speed at 10 m height on open terrain with = 0.03 m and = 0 m | |||||

[m s] | wind velocity components ( is due north, west, upwards) | |||||

[m s] | wind velocity vectors according to the anemometer axis system | |||||

[ml] | effective volume of a rain gauge bucket | |||||

[m s] | terminal drop speed | |||||

[kg m] | liquid water content (i.e. amount of liquid water per unit of air) | |||||

[m] | building width | |||||

[m] | position coordinates ( is upwards) | |||||

-axis quantity and -axis quantity of the fit function , in correlation plots | ||||||

[m] | roughness length |

coefficient in Lacy's formula 2.29 | ||||||

coefficient in model 2 (eq. 5.4) | ||||||

exponent in Lacy's formula 2.29 | ||||||

exponent in model 2 (eq. 5.4) | ||||||

constant in eq. 6.8 | ||||||

exponent in model 2 (eq. 5.4) | ||||||

[m s] | dissipation rate of | |||||

[-] | catch ratio (eq. 2.26) | |||||

[] | constant in function (fig. 5.23) for model 2 (eq. 5.4) | |||||

[] | angle (in chapter 6) | |||||

[-] | obstruction factor, eq. 2.35 | |||||

[m] | parameter in [Marshall and Palmer 1948] drop spectrum (eq. 2.21) | |||||

parameter in [Ulbrich 1983] drop spectrum (eq. 2.23) | ||||||

[kg m s] | dynamic viscosity (1.6-1.8 10 kg m s for air), | |||||

[m s] | kinematic viscosity (1.3-1.5 10 m s for air), | |||||

[m s] | turbulent or eddy viscosity | |||||

[-] | constant in function (fig. 5.23) for model 2 (eq. 5.4) | |||||

[kg m] | density | |||||

[-] | - model constant | |||||

[-] | - model constant | |||||

[N m] | turbulent shear stress | |||||

[N m] | surface shear stress (eq. 2.2) | |||||

[kg m s m] | raindrop mass flux spectrum (definition of in eq. 2.16) | |||||

[] | horizontal wind direction, angle from which the wind blows, clock wise from north (e.g. 270 is wind from west) |

5, 10, 60 | clock period 5, 10 and 60 min respectively | |||||

air | ||||||

corrected, esp. for rain intensity: rain intensity is obtained by combining data of a tipping-bucket rain gauge and a rain indicator (see section 3.4.3) | ||||||

raindrop | ||||||

estimate (eq. 3.4) | ||||||

at façade | ||||||

horizontal (at reference unless otherwise indicated) | ||||||

measurement (eq. 3.4) | ||||||

P1, P2, ... |
measurement positions | |||||

reference | ||||||

uncorrected, esp. for rain intensity: rain intensity is obtained by simply counting the tippings of a tipping-bucket rain gauge (see section 3.4.3) | ||||||

vertical (at reference unless otherwise indicated) |

mean of | ||||||

fluctuating component of ( ) | ||||||

standard deviation of | ||||||

for , and by for the other values of , where is limited to the interval 0-1 (fig. 5.23) |

ISBN 90-6814-569-X

Published as issue 69 in the