Variations in atmospheric aerosol concentration of various sizes during the total solar eclipse of 22 July 2009 over a semi urban tropical site of Northern India

The effect of total solar eclipse on aerosol size and concentration has been studied. Continuous measurements of aerosol particle concentration having various sizes (0.3-0.5, 0.5-1.0, 1.0-2.0 and 2.0-5.0 mu m) along with some meteorological parameters in conjunction with total solar eclipse of 22 July 2009 have been made from 21 to 23 July 2009 at Roorkee (29A degrees N, 77A degrees E, 275 m above sea level). It has been observed at Roorkee 90 % maximum obscurity of eclipse since it is close to the path of totality. The event started from 05:28 h LST and ended at 07:42 h LST with total eclipse at 06:30 h LST. Results of the measurements show an increase in aerosol number concentration in sub-micron and micron size ranges during eclipse with respect to those made on any other day.