The sailors cannot calm the storm. Rather, the storm can overpower the sailors. Thus the storm not only frightens them because of its effects, its threat to kill them, but it also adds another level of fear. They cannot control it or resolve it and so feel extra afraid.The Turkish fleet, in contrast, does not constitute an uncontrollable threat. They can attack autonomously, but they are also opposable by the other soldiers. So fear works on only one level in this instance. It operates in that controllable and resolvable type of fear rather than the uncontrolled tempest sort. This reminds me of issues in my life, some of which I feel in control and some out of control.
The “storms” of life include certain forms of illness or my moods. These things come and go as they please, and remedy is often useless. However, other fears I can fight against. For example, if I am nervous about an upcoming test, I can study more or find help. This sooths the anxiety and fear of the test taking. Likewise, if I am afraid of how someone might respond to me, I can take every effort to speak kindly and appropriately in order to lower the chances that they will produce a negative response. The second act of Othello features these types of fears that still occur in modern living.