Azur refers to a deep, clear blue color, often associated with the sky or sea. While it's a color, it's less common than 'bleu' and carries a more poetic and evocative feel.
In the lyrics, "Quand les éclairs déchirent l'azur" (When the lightning tears through the azure), it paints a vivid and dramatic image of a stormy sky. This word adds a touch of elegance and intensity to the description, making it stand out.
"Viens" ("Come") is Charles Aznavour singing to someone he loves during a storm, asking her to come closer while the rain falls and the thunder rolls. He promises to hold her, keep her warm, and shield her from the fear the storm brings.
But the shelter is only for the night. He already knows that when the sun comes up, she will leave, just as surely as the rain will pass. The song holds both feelings at once: the comfort of being close to someone right now, and the quiet sadness of knowing it will not last past sunrise.
It is a classic Aznavour theme: love as something intense but fleeting, worth living fully even when you know how it ends.