The speaker of the poem describes love as "an ever-fixed mark / That looks on tempests and is never shaken," personifying the quality of love but also presenting a visual image of someone who will watch the development of terrible storms without trembling or becoming fearful. The use of the word "tempests," especially, lets us know that this is a raging, chaotic storm, not just some glorified rainfall. The word choice of "tempests" implies dark clouds, whirling winds, and torrential rains blowing in all directions.
The speaker also describes love as "the star to every wand'ring bark, / Whose worth's unknown, although his height be taken." Here we have another visual image of a star to which a man onboard a ship or far from home might look for a sense of safety or security. It is something constant, or at least predictable, that he can locate in order to know where he is.
The speaker employs more visual imagery when he refers to love's "rosy lips and cheeks" and time's "bending sickle." We can easily see in our mind's eye a young person in love, with flushed face when they see their beloved. Likewise, the description of time, and the weapon it uses to mow down life when it reaches the end, is likewise clear. You can imagine the curved shape of the blade a reaper would use to harvest crops, just as time harvests lives.