共查询到20条相似文献,搜索用时 15 毫秒
1.
《Journal of Atmospheric and Solar》2008,70(16):2000-2004
Atmospheric ionization rate for the incident electrons and heavy nuclei (protons and α-particles) of various origin is simulated using GEANT4 code. The photon-nuclei cascade generated by a primary particle is included in this code. “Secondary” bremsstrahlung effect from electrons causes peak ionization at low altitudes along with the more powerful peak at high altitudes. The contribution of helium to the total ionization rate, which turns out to be ∼10% of that of protons, is discussed. 相似文献
2.
The surface tension lowering by surface-active substances has been measured on rainwater, melted snow, and dispersions of
atmospheric particles in water, with a film balance and a tensiometer. The precipitation water was sampled during 1979, 1980,
and 1981 in the city of Frankfurt/Main. From measurements with the film balance technique, normalized concentrations of insoluble
and weakly soluble surface-active substances have been estimated. Soluble surface-active substances were determined from measurements
with a tensiometer.
It was found that the normalized concentration of theinsoluble and weakly soluble surface-active material on rainwater or melted snow shows a maximum during late spring of about 2.5 · 10−7 moles/l and a minimum during wintertime of about 5 · 10−8 moles/l. These concentrations are too low to influence significantly the condensation of water vapour on cloud droplets or
the evaporation of water from them. Thesoluble surface-active material on rainwater or melted snow was found to have concentrations of the order of 2 · 10−6 moles/l. These concentrations are also too small to have a significant influence on cloud physical processes. 相似文献
3.
4.
The possible mechanism by which cosmic rays affect the formation of neutral water droplets and ice crystals in the Earth’s
atmosphere has been considered. This mechanism is based on changes in atmospheric transparency and vertical temperature distribution.
It has been indicated that a change in the optical thickness for visible and IR radiation by several percents, which can take
place when cosmic-ray particles penetrate into the atmosphere, results in a change in the temperature vertical distribution,
affecting the growth of water droplets, concentration of active condensation nuclei, and the formation of ice particles. This
mechanism makes it possible to explain the correlation between the intensity of galactic cosmic rays at low altitudes and
the absence of this correlation at middle altitudes. 相似文献
5.
6.
Gottfried Hänel 《Pure and Applied Geophysics》1977,115(4):775-797
The dependency on relative humidity of the settling velocity of aerosol particles in stagnant air and of the diffusion coefficient due to Brownian motion of aerosol particles was computed for six aerosol types and different particles sizes in dry state. The computations are based (1) on mean bulk densities of dry aerosol particles obtained from measurements or from the knowledge of the chemical composition of the particles, (2) on micro-balance measurements of the water uptake per unit mass of dry aerosol substance versus water activity at thermodynamic equilibrium, and (3) on measurements of the equilibrium water activity of aqueous sea salt solutions. The results show a significant dependence of the settling velocity and Brownian diffusion of aerosol particles on relative humidity and on the particle's chemical composition.Nomenclature
A
surface parameter of a particle
-
B
surface parameter of a particle
-
c
L
velocity of sound in moist air
-
C
1+Kn[A+Qexp(–B/Kn]=slip correction
-
D
diffusion coefficient of a particle
-
D
1
D(=1)=diffusion coefficient of a spherical particle
-
f
P
w
/P
we
(T,P)=relative humidity (f=0 dry air,f=1 saturated air)
- g
acceleration due to gravity
-
g
|g|
-
k
1.3804×10–16 erg/°K=Boltzmann constant
-
Kn
L
/r=Knudsen number of a particle
-
Kn
0
0L
/r
0=Knudsen number of a dry particle
-
m
4r
3/3=mass of a particle
-
m
L
4r
3
L
/3=mass of the moist air displaced by a particle
-
M
mobility of a particle
-
M
0
molar mass of dry air
-
M
w
molar mass of water
-
Ma
|u–u
L
|/c
L
=Mach number of the particles motion relative to the ambient air
-
n
particle number per unit volume of air
-
P
P
0+P
w
=pressure of the moist air
-
P
0
partial pressure of the dry air
-
P
w
partial pressure of the water vapour
-
P
we
P
we
(T,P)=equilibrium partial water vapour pressure over a plane surface of water saturated with air
-
Q
surface parameter of a particle
-
r
equivalent radius of a particle (radius of a sphere with the particles volume)
-
r
0
equivalent radius of a particle in dry state
-
R
1+0.13Re
0.85=inertia correction
-
R
0
specific gas constant of dry air
-
R
w
specific gas constant of water
-
Re
2r
L
u–u
L
/
L
=Reynolds number of the particles motion relative to the ambient air
-
t
time
-
T
absolute temperature
- u
velocity of a particle
-
u
(amount of the) settling velocity of a particle in stagnant air
-
u
1
u(=1)=(amount of the) settling velocity of a spherical particle in stagnant air
- u
L
velocity of the ambient moist air (far enough from the particle where the flow pattern remains undistorted)
-
W
drag coefficient of a particles equivalent sphere
-
empirical parameter in equation (3.1)
-
dynamic viscosity of a particles liquid cover
-
L
dynamic viscosity of moist air
- 0L
dynamic viscosity of dry air (at the same pressure and temperature like the moist air)
-
celsius temperature
-
dynamic shape factor of a particle (=1 for a sphere)
- 0
dynamic shape factor of a dry particle
-
L
mean free path of the molecules in moist air
- 0L
mean free path of the molecules in dry air (at the same pressure and temperature like the moist air)
-
Po
mean free path of the molecules in dry air at the pressureP
0 of the dry air and the temperature given
-
factor of solid to liquid change-over (=1 for a solid particle)
-
mean bulk density of a particle
-
L
density of the moist air
- 0L
density of the dry air at the same pressure and temperature like the moist air
- 0
mean bulk density of a dry particle
- 0
mean diameter of the molecules of dry air
-
w
diameter of water molecules
-
relaxation time of a particle
-
gradient operation
-
3.141593 相似文献
7.
Wendy Freedman 《Astronomy& Geophysics》2002,43(1):1.10-1.13
Wendy Freedman presents the 2001 George Darwin Lecture on present and future advances in cosmology.
Modern cosmology is undergoing an explosion of observational and experimental results that is in turn driving significant theoretical advances and a dynamic interface between theory and experiment. As a consequence, cosmological parameters are becoming much more precisely constrained. In this, the George Darwin lecture for 2001, I look back at the some of the advances made since Edwin Hubble presented his George Darwin lecture in 1953, and look ahead to the resolution of significant cosmological uncertainties. 相似文献
Modern cosmology is undergoing an explosion of observational and experimental results that is in turn driving significant theoretical advances and a dynamic interface between theory and experiment. As a consequence, cosmological parameters are becoming much more precisely constrained. In this, the George Darwin lecture for 2001, I look back at the some of the advances made since Edwin Hubble presented his George Darwin lecture in 1953, and look ahead to the resolution of significant cosmological uncertainties. 相似文献
8.
By the experiment, it is confirmed that water-marble rock system shows obviously chemical anomalous behaviors: the relevant
minerals which formed marble rock are resolved fast, water becomes alkaline, meanwhile H2 emission appears under action of ultrasound; based on rock identification by microscope and chemical analysis of water and
rock, the mechanism of above chemical reaction is analyzed and discussed.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15 498–507, 1993.
This study was supported by the Chinese Joint Seismological Science Foundation. 相似文献
9.
10.
针对高层钢筋混凝土框架支撑结构体系,运用结构塑性极限分析原理给出了在水平地震作用下最可能出现的破坏机构及相应的极限荷载半解析度,根据上限定理求出水平地震作用下一榀框架支撑体系各种破坏机构的最小破坏荷载。再根据刚度分配原则,可计算出整个结构不形成机动体系所能承担的最大水平地震作用。 相似文献
11.
Dr. B. J. Mason 《Pure and Applied Geophysics》1957,36(1):9-20
Summary Our present knowledge concerning the abundance, size, physical properties, origin and nature of condensation nuclei is reviewed and critically assessed. 相似文献
12.
Thermal diffusivity, k, of three lunar rocks (10049 and 10069; Type A, Apollo 11 and 14311; Apollo 14) and a terrestrial basalt (alkaline olivine basalt, Oki-do?go, Japan) was measured under one atmosphere and in vacuum conditions (10?3 ~ 10?5 mmHg) in the temperature range from 85 to 850°K. The semi-empirical curve of k =A + B/T +CT3 is fitted to the data in each condition. The porosity of rocks strongly affects the thermal diffusivity at low temperature ( T ? 500°K) in vacuum condition. At 150°K, thermal diffusivity of lunar rocks with porosity of 5.5% (10049) and 11% (10069) at one atmosphere is about 1.7 and 3.2 times of that in vacuum, respectively. The difference between the values at one atmosphere and those in vacuum decreases as the temperature increases. Measurements of k should be made at gas pressures at least lower than 10?3 mmHg to estimate the value under lunar surface conditions. 相似文献
13.
The phenomenological model of condensation interaction between galactic cosmic rays (GCRs) and water vapor, which makes it possible to estimate atmospheric pressure variations at different altitudes with changing GCR flux, has been developed. It has been indicated that pressure should increase at all altitudes in the considered interval (0–5 km above sea level) during Forbush decreases. Therefore, the correlation between pressure and GCR flux under mountain conditions can be negative as near sea level. However, the performed calculation of the cross-correlation function of the series of daily data, obtained at Jungfraujoch station (3475 m) in 1968–1992, indicated that this correlation is positive and statistically significant with a maximum leading the GCR variation onset by two days. As usual, pressure increased during Forbush decreases due to the condensation mechanism. The obtained results can be explained by the manifestation of the optical mechanism related to solar flares, which operates together with the condensation mechanism and causes a decrease in pressure at high altitudes. It has been indicated that the effectiveness of this mechanism substantially changes with the phase of the quasibiennial cycle. 相似文献
14.
Donald A. Drew 《Pure and Applied Geophysics》1976,114(3):333-344
Summary The zonally asymmetric stationary component of the general circulation is studied for small Rossby number without the beta-plane approximation. The equations for this component are linearized about a mean flow. An analytic solution for the meridional wind is found when the zonal wind and static stability of the mean flow are independent of the vertical coordinate. The solution is used to compute the transports of angular momentum and heat. The angular momentum transports give rise to a net convergence of the order of Rossby number and are balanced by the zonal mean Coriolis torque. However, the heat transports vanish at this order of magnitude. 相似文献
15.
Eduard Petrovský Radek Zbořil Tomáš Matys Grygar Bohumil Kotlík Jiří Novák Aleš Kapička Hana Grison 《Studia Geophysica et Geodaetica》2013,57(4):755-770
Magnetic measurements of deposited atmospehric dust can serve as an additional parameter in assessing environmental pollution. This method is based on the assumption that atmospherically deposited particles contain significant portion of ferrimagnetic iron oxides of anthropogenic origin, which can be easily detected. Aim of this paper is to identify clearly magnetic fraction of daily samples of particulate matter less than 10 μm (PM10), routinely used for air quality assessment and monitoring. We used combination of thermomagnetic analyses and other physical and chemical methods, including scanning electron microscopy (SEM) and Mössbauer spectroscopy. Our results show that daily samples of PM10, collected at sites with different degree of atmospheric pollution, contain magnetite of spherical shape, which is presumably of industrial origin. Thus, magnetic methods can be applied directly to the same substances, which are used routinely in air quality assessment and monitoring. 相似文献
16.
17.
Fanbing Xue 《中国科学D辑(英文版)》1998,41(6):586-591
In consideration of the characteristics of spectral average of the Rossby wave trains and the adoption of a climatic mean
stream field as the basic stream field, an approximate analytical formula for the period of atmospheric low-frequency oscillation
(LFO) and the group velocity is deduced from a barotropic and non-divergent linearized vorticity equation. All the action
centers of atmosphere are found to be the oscillators of low frequency. The LFO propagates southward across the streamlines
in the wind field with a southward component or propagates northward across the streamlines in the wind field with northward
component instead of along a great circle. The switch of the propagation direction takes place near the top of ridge or the
bottom of trough. The angle between the wave rays and the zonal direction can be determined.
Project supported by the National Natural Science Foundation of China (Grant No. 49175241). 相似文献
18.
Mean bulk densities of various samples of dry atmospheric aerosol particles sampled at different sites and during different seasons and weather situations range between 1.8 and more than 3 gm cm3. 相似文献
19.
20.
近断层地震动脉冲特性在2个水平分量上具有差异,采用平方和开方法分析了近断层脉冲地震动双向地震作用下基础隔震结构和组合隔震结构的隔震层位移,并与近断层脉冲单向地震作用进行了对比分析,结果表明:若仅地震动加速度峰值大的分量或2个方向分量均存在明显速度脉冲,则产生的隔震层位移大于单向地震动;若仅地震动加速度峰值小的分量存在明... 相似文献