Rashi citing Shabbos 151b: This is the forehead, which illuminates and is Matzheves (shows happiness) in a youth. When he gets old, it wrinkles and is not Matzheves.

Rashi (6, from Eichah Rabah): This is [before will cease] Malchus Beis David - "v'Chis'o cha'Shemesh Negdi" (Tehilim 89:37).

Rashbam: Before the world darkens for you, and the luminaries will not illuminate for you, for you are close to death - repent.

Rid: In old age, the entire world seems dark, like on a cloudy day.

Seforno: Before the heart darkens due to excess black fluid.

Metzudas David: Before the sun sets and the light [departs]. I.e. before you get ill and bedridden. When illness worsens, it seems that the sun and light darken.

Rav Sadya Gaon: It is its (the sun's) light.

Rashi citing Shabbos 151b: This is the nose, which is the form of the face.

Rashi (6, from Eichah Rabah): It is Torah - "v'Sorah Or" (Mishlei 6:23).

Ibn Ezra: It is the light of dawn, before the sun shines.

Seforno: The Ru'ach Chiyuni in a person.

Rashi citing Shabbos 151b: It is the Neshamah, which illuminates man. Once it is taken, he has no sight.

Rashi (6, from Eichah Rabah): It is the Sanhedrin, which sat like a granary in a half-circle (Sanhedrin 36b, i.e. a crescent).

Seforno: It is the brain, which receives Ohr Chiyuni from the heart.

Rashi citing Shabbos 151b: These are the jaws, the pomegranates of the face (Avodah Zarah 30b); they are Matzhivim.

Rashi (6, from Eichah Rabah): They are Rabanan - "u'Matzdkei ha'Rabim ka'Kochavim" (Daniel 12:3).

Seforno: They are the external and internal senses.

Ibn Ezra #1: There are creations such as birds (bats) that cannot fly during the day due to the sun ¹ .

Ibn Ezra #2: Verses often go in ascending or descending order, e.g. "Hine Lo Yanum v'Lo Yishan" (Tehilim 121:4) - Tenumab is lighter than Shenah ² .

Rashi citing Shabbos 151b: It is sight, which deteriorates due to crying ¹ [over a person's waning faculties as he ages].

Rashi (6, from Eichah Rabah): An affliction after a difficult affliction. All Yirmeyah's harsh Nevu'os were fulfilled only after Churban ha'Bayis.

Rav Sadya Gaon: The clouds return immediately after the rain.

Ibn Ezra #1: This is when a person has too much fluid.

Ibn Ezra #2: When a Choleh dies, his world darkens, and it seems that clouds hide the light.

Rashbam: It is darkness after darkness - "Albish Shamayim Kadrus" (Yeshayah 50:3). Amidst the great affliction, it seems that the world is dark for them. Initially when the rain fell there were clouds. It rained, and it became light. After, clouds and darkness returned ² .

Seforno: These are vapors that return [from the rain, and form clouds].