Table 4.

Average pair-wise correlation and standard deviation between visibility and each meteorological variable.

	Monthly mean temperature	Monthly mean atmospheric pressure	Monthly mean relative humidity	Monthly total rainfall	Monthly mean wind speed
Visibility	−0.600* (0.173)	0.505 (0.196)	−0.076 (0.312)	−0.442 (0.199)	0.072 (0.269)

(i) The sample size of each pair is 12 i.e. 12 months. (Average values from 1971 to 2011).

(ii) * for p < 0.05; ** for p < 0.01; *** for p < 0.001.

(iii) The values of standard deviations are shown in bracket.