Answer: The participle is "Falling".
Step-by-step explanation: Participle, according to the dictionary, is "a form of verb, often ending in '-ed' or 'ing' and used with auxiliary verbs to make verb tenses, or is used as adjectives".
When it is used as a verb, it can be used as perfect tenses (combined the verb in the past tense with the verb 'have', in its present or past form) or passive voice (object of the action + verb to be + past participle + preposition by + subject who made the action). When it is used as an adjective, it depends on the context it is inserted.
In the question above, the participle is 'Falling' and it is an adjective, because it is describing the noun 'snow'.