Green stripe represents Sim's mood. The better mood the better, he or she learns new skills faster (or acquires their higher levels) and he or she performs job better (so there are better chances for promotion). Its satisfaction depends on the things that Sim experiences. Icons represent the influence and below there is time of this influence left. Positive mood can be caused ex. from good fun, being in a well decorated house or a bath . If the time doesn't appear under the icon, it means it is caused by present situation, ex. Sim is dirty (the mood will disappear when he or she takes a bath), sits in a comfortable armchair or lies in a comfortable bed (moodlet will disappear when he or she gets up).
Moodlets can be positive (green), negative (red) or neutral (blue). The last ones inform about some facts ex. Sim is too tired to do more exercises , or that Sim has to go to toilet soon (if you neglect it negative moodlet meaning you need to go to toilet will appear).
Of course the time the moodlet lasts depends on its importance ex. Sim woken up by a crying baby will have a bad mood only for an hour but the one who got married will be happy for two days .
The influence of moodlet differ not only in their length but also in their strength of influence. It is presented when the arrow is on the moodlet .
Moonlets mainly depend on Sim's personality - traits he or she possesses. Sim Lucky may wake up in the morning with a positive moodlet of luck which will make him or her feel better during the day. Lonely Sim is happy when he or she is alone - after a moment positive moodlet of loneliness appear . However, when you choose a place with bigger number of people, ex. office building or library Sim will feel discomfort (negative moodlet being in a crowd ).
Buying new things, fulfilling everyday needs and dreams of Sims - it all influences their mood and there are hundreds of moodlets.