What is the main topic of the conversation?

M: It looks like there is going to be a shower any minute now.
    W: I think so too. Isn’t it strange how you can sense it?
    M: I know what you mean.
    W: Look at the clouds in the sky. Whenever they seems dark and low like this, you know it’s going to rain. Or look at the object that’s far away. If it seems clear to you, it’s going to pour.
    M: Yes. And everything seems to have a strange smell to me then.
    W: I know. And people often say it’s going to rain when they have aches and pains in certain parts of their body. My mother always complains that her knee hurts just before a storm.
    M: And have you ever noticed how the animals act before a storm?
    W: Sure. Horses and cows always seem to go to a protected area and huddle together.
    M: Yeah. But with all these sensible signs, how can we carry an umbrella with us now?