Answer:
If it is raining and your on wet land
The thunderstorm lightning is generated by the collision of the charged clouds in the earth's atmosphere. It has a tendency to flow to the earth because it acts as a reservoir for the electrical charges.
In the following condition a person is prone to be struck by lightning:
When a person is standing below tall buildings having no provision of dissipating the electrical lightening because it provides a low resistance path for the flow of charge to the earth.
When a person is standing below a tall tree it also provides low resistance and high conductivity path for the charges to flow to the reservoir earth.