21. scattering cross-section of acrosol particles is 2.5e-12 m , absorption cross-section is 0.45e- .2 12 m concentration of particles is n 2e7 1/m. calculate the optical thickness and transmittance of atmosphere at this wavelength if sun zenith angle is 40 degrees and the thickness of aerosol layer is 2.5 km.

In a 2010 article “fact check: eastern u.s. earthquake risk” by chris mould, the author provides as evidence the following statement by the united states geological survey: “although earthquakes may be less frequent in the eastern u.s., … urban areas in the east could face bigger losses because the shaking would affect much larger areas than similar quakes in the west. in addition, most homes and buildings in the east are not designed to withstand earthquakes.”this statement directly relates to which of the following concepts? a. vulnerabilityb. hazardc. riskd. severity

Explain the value of statistics and other data to positive economics and to normative economics

Venezuela’s economy relies most heavily on which of the followingvenezuela’s economy relies most heavily on which of the following? a. oil reserves in places such as the eastern llanos b. cattle ranching in the grasslands c. fertile farmland in the andean highlands d. coffee plantations in mountainous areas