Lightning

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1.     Average number of days per year with thunderstorm occurrence, based on data from 1971-2000 (Provincial Overview). Source: Environment Canada, 2003a
2.     Average number of days per year with cloud-to-ground lightning, based on data from 1999-2008 (Ontario). Source: Burrows et al., 2002; Burrows and Kochtubajda, 2010; Environment Canada, 2010.; Kochtubajda and Burrows, 2010
3.     Average number of days per year with cloud-to-ground lightning, based on data from 1999-2008 (Southern Ontario). Source: Burrows et al., 2002; Burrows and Kochtubajda, 2010; Environment Canada, 2010.; Kochtubajda and Burrows, 2010
4.     Average annual flash density (number of flashes/km2/year) from cloud-to-ground lightning, based on data from 1999-2008 (Ontario). Source: Burrows et al., 2002; Burrows and Kochtubajda, 2010; Environment Canada, 2010.; Kochtubajda and Burrows, 2010
5.     Average annual flash density (number of flashes/km2/year) from cloud-to-ground lightning based on data from 1999-2008 (Southern Ontario). Source: Burrows et al., 2002; Burrows and Kochtubajda, 2010; Environment Canada, 2010.; Kochtubajda and Burrows, 2010

Sources
Burrows, W. R. and B. Kochtubajda, 2010. A Decade of Cloud-to-Ground Lightning in Canada: 1999-2008. Part 1: Flash Density and Occurrence. Atmosphere-Ocean 48 (3) 2010, 177-194.
Burrows, W. R., P. King, P.J. Lewis, B. Kochtubajda, B. Snyder and V. Turcotte, 2002. Lightning Occurrence Patterns over Canada and Adjacent United States from Lightning Detection Network Observations. Atmosphere-Ocean 40 (1) 2002, 59-81.
Environment Canada, 2003a. National Climate Data and Information Archive. Available online: http://climate.weatheroffice.ec.gc.ca/climate_normals/index_e.html
Images used with the permission of William R. Burrows, Research Scientist, Environment Canada.
Kochtubajda, B. and W. R. Burrows, 2010. A Decade of Cloud-to-Ground Lightning in Canada: 1999-008. Part 2: Polarity, Multiplicity and First-Stroke Peak Current. Atmosphere-Ocean 48 (3) 2010, 195-209.

Data from ontario.hazards.ca