There is a real disorder called SAD (seasonal affective disorder). Your mood is affected by the weather,season etc. When it is cold,cloudy,rainy your mood is reflective of this. When it is warm,sunny and clear you are happier,more energetic and in a good mood. I have it and that is why I moved from the north where it is cold and dreary 6 months out of the year. I am a much happier person now.