United States Patent 5,003,186
Chang , et al. March 26, 1991
Stratospheric Welsbach seeding for reduction of global warming
A method is described for reducing atmospheric or global warming resulting from the presence of heat-trapping gases in the atmosphere, i.e., from the greenhouse effect. Such gases are relatively transparent to sunshine, but absorb strongly the long-wavelength infrared radiation released by the earth. The method incudes the step of seeding the layer of heat-trapping gases in the atmosphere with particles of materials characterized by wavelength-dependent emissivity. Such materials include Welsbach materials and the oxides of metals which have high emissivity (and thus low reflectivities) in the visible and 8-12 micron infrared wavelength regions.
Inventors: Chang; David B. (Tustin, CA), Shih; I-Fu (Los Alamitos, CA)
Assignee: Hughes Aircraft Company (Los Angeles, CA)
Appl. No.: 07/513,145
Filed: April 23, 1990
Current U.S. Class: 250/505.1 ; 244/158.1; 250/503.1; 250/504R
Current International Class: A01G 15/00 (20060101); G21K 001/00 ()
Field of Search: 250/505.1,54R,503.1,493.1 244/136,158R
References Cited [Referenced By]
U.S. Patent Documents
3222675 December 1965 Schwartz
4755673 July 1988 Pollack et al.
Primary Examiner: Berman; Jack I.
Attorney, Agent or Firm: Sales; Michael W. Denson-Low; Wanda
What is claimed is:
1. A method of reducing atmospheric warming due to the greenhouse effect resulting from a layer of gases in the atmosphere which absorb strongly near infrared wavelength radiation, comprising the step of dispersing tiny particles of a material within the gases’ layer, the particle material characterized by wavelength-dependent emissivity or reflectivity, in that said material has high emissivities with respect to radiation in the visible and far infrared wavelength spectra, and low emissivity in the near infrared wavelength spectrum, whereby said tiny particles provide a means for converting infrared heat energy into far infrared radiation which is radiated into space.
2. The method of claim wherein said material comprises one or more of the oxides of metals.
3. The method of claim 1 wherein said material comprises aluminum oxide.
4. The method of claim 1 wherein said material comprises thorium oxide.
5. The method of claim 1 wherein said particles are dispersed by seeding the stratosphere with a quantity of said particles at altitudes in the range of seven to thirteen kilometers above the earth’s surface.
6. The method of claim 1 wherein the size of said particles is in the range of ten to one hundred microns.
7. The method of claim wherein said material comprises a refractory material.
8. The method of claim 1 wherein said material is a Welsbach material.
9. The method of claim 1 wherein the number of said dispersed particles per unit area in the particle layer is greater than or equal to 1/.sigma..sub.abs 1, where 1 is the thickness of the particle layer and .sigma..sub.abs is the absorption coefficient of the particles at the far infrared wavelengths.
10. A method for reducing atmospheric warming due to the greenhouse effect resulting from a greenhouse gases layer, comprising the following step:
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