Poem with an explanation: silver clouds

one hundred and fifty
over ninety
the silver clouds form

This poem is about blood pressure.

The poem describes a situation of high blood pressure.  The blood pressure is one hundred and fifty over ninety.  This is related in the first two lines of the poem.

This reading causes the person who has it to worry.  Their worry is described as “silver clouds” in the poem.  The silver clouds forming quickly is a reference to a name for the element mercury: quicksilver.  Blood pressure can be measured in millimeters of mercury and this relates to that.