Fog is a type of Weather. Fog is related to Condition. Condition is related to Factor. Factor is a type of Calculate. 
Contribute is a synonym of Lend. Factor is a type of Lend. Factor is a synonym of Agent. 
Weather <--IsA-- Fog <--RelatedTo--> Condition <--RelatedTo--> Factor --IsA--> Calculate 
Contribute <--Synonym--> Lend <--IsA-- Factor <--Synonym--> Agent 