Closer Examination

What On Earth: As the dust affects the atmosphere? Wilcox: Well, we know that the dust – it is not just a passive particle floating in the surrounding area. We also know that it can absorb or reflect sunlight. Dust emissions certainly cooled the planet by reducing the amount of sunlight that reaches its surface. Moreover, we know that dust can heat the atmosphere, although the degree of heating did not significantly set. What On Earth: What influences the fact that the particle will absorb rather than reflect the light? Wilcox: This is the color of the particles and, to some extent, with its shape. For more specific information, check out AG1. We call this property is the single scattering albedo, which, in essence, represents a the probability that a photon of light is more likely to disperse than absorbed. If the scattering is very high – say, 0.99 – we do not doubt that 99 out of 100 photons will be reflected.

If the scattering is less than, say 0.85, it means that there is a 15 – percent chance that the photon will be absorbed. More info: Caldwell Esselstyn Jr.. What On Earth: Which model is valid for the dust of the Sahara Desert? Wilcox: Some of the dust Sahara – absolutely brilliant, and some – very dark. It depends on whether was brought from the sand and what is its mineralogy. What On Earth: Why the absorption of light by dust is of such importance? Wilcox: We have found that dust emissions, along with other factors, seem to shift the front of tropical precipitation precipitation (which usually fall on a narrow strip at the collision point of winds of the northern and southern hemispheres) north for about four or five degrees, the width is about 240 – 280 miles over the equator. What On Earth: Really? What attitude has dust to precipitation? Wilcox: The main trajectory of the dust from the Sahara, in most cases lies significantly north of the strip of Atlantic tropical downpours. At the same time, simultaneously with sand (dust) storms are strong heating of the lower atmosphere, thus the circulation of air over the ocean responds to this heating variable wind and distribution of rainfall in a northerly direction in the year period. The amount of precipitation depends on the passage of dust storm, even if the dust is not mixed with rain. What On Earth: Will the upcoming mission of Gloria (Glory) in the study of this phenomenon? I know that it has a device which will measure aerosols, such as dust? Wilcox: Certainly.

On the bright reflective surfaces such as desert – where it is almost impossible to distinguish aerosol from the surface – for us will be useful, any new information. What On Earth: What is the significance of migration to the north of precipitation during the dust storms? Wilcox: Certainly, people living in the area, interested in understanding how dust affects the distribution of rainfall in their area. The data obtained also support the idea expressed by one of my colleague – Bill Law (Bill Lau) – who has been studying the overhead heat pumps. The idea is that aerosols from dust storms and air pollution really affect the occurrence of monsoons. Space Flight Center. 'What an interesting time we can expect in the future', – exclaims Ofer.