Understanding Emotional State Through Stage Directions

In a dramatic play, the stage directions serve as critical tools for interpretation, providing insights into characters' emotions and actions.

Examine the following segment from a play's stage directions:

As the curtain rises, a dim light reveals ANNA sitting quietly at a small table, her hands trembling. The sound of distant thunder rumbles ominously.

Based on this excerpt, what can be inferred about Anna's emotional state as she interacts with her environment?