The sun can't talk. A fish can't pray. How are they supposed to "praise" God?
This psalm gives orders to things that cannot hear them. Sun, praise Him. Snow, praise Him. Cedar trees, praise Him. The commentators saw the problem.
Radak (Rabbi David Kimchi, Provence, around 1200) says the word is not a command here. It is like saying: it is fitting for you to praise. Meiri (Rabbi Menachem Meiri, Provence, around 1300) adds that Hebrew often uses the command form for something that is simply always so. Tanach even talks this way, he says, to things that cannot praise at all: "all the trees of the forest will sing."
For the sun, moon and stars, the Rambam (Maimonides, Egypt, 1100s) holds that the praise is real. In the Mishneh Torah (his code of law) he writes that the stars and the spheres that carry them are alive and aware. They know their Creator and praise Him the way angels do. In the Guide for the Perplexed (his book of philosophy) he says this is what the philosophers taught, and that the Torah agrees. He adds that this praise has no words. Understanding is the praise.
The bottom half is different. Fire, wind, water and earth, the Rambam writes, have no soul and know nothing. They are like dead bodies. So what does David mean by "Praise Hashem from the earth, sea giants and all deep waters, fire and hail"? He means: people, praise Him for the power you see in the fire and the hail. Radak says the same about the sea creatures. They have no mind. People will praise because of the wonders they see in them.
So the earth's half has one voice, the human one. Radak says it outright on verse 13: the ones who have minds praise for themselves and for the rest of creation.
Midrash Tehillim (a collection of rabbinic teachings on Tehillim) does not make that split. Everything praises God, it has David say. If a person does not want to thank and praise his Creator, the crawling thing and the bird thank Him. Its proof is a verse in Yeshayahu: "The wild animal will honor Me."
Radak on Tehillim 148:1, 148:7 and 148:13,Meiri on Tehillim 148:1,Rambam, Laws of the Foundations of the Torah 3:9 and 3:11,Rambam, Guide for the Perplexed 2:5 (Ibn Tibbon's Hebrew),Midrash Tehillim, on Tehillim 148:10Storm wind "does His word." So is every hurricane a punishment?
Verse 8 lists fire, hail, snow and steam, and then "storm wind that does His word." Anyone who has seen the news after a hurricane will stop on that line.
Radak (Rabbi David Kimchi, Provence, around 1200) takes it at full strength. A storm wind, he writes, knocks down tall cedars, buildings and ships at sea. The verse says it "does His word" to teach that this is not chance. God commands the wind to blow, and it blows to punish those it reaches. Rashi (the classic commentator, France, 1000s) is close to that. Retelling the Gemara's story of David and the hail, he calls the things on this list kinds of punishment.
Two later commentators add one word. Meiri (Rabbi Menachem Meiri, Provence, around 1300) writes that the wind is sometimes sent to punish. Malbim (a rabbi and commentator of the 1800s) writes that the storm is sometimes ready for God's mission. Sometimes is not always.
The Rambam (Maimonides, Egypt, 1100s) draws the line in another place. In the Guide for the Perplexed (his book of philosophy) he uses this exact case: a storm sinks a ship. He does not believe a leaf falls by a decision about that leaf, and he allows that the sinking itself may be plain chance. What is not chance, in his view, is that those people boarded that ship. That follows God's judgment. He adds at once that our minds cannot reach the rules of that judgment.
So the sources do not hand you one answer. Radak hears a command in the storm. Meiri and Malbim hear one in some storms. The Rambam says nature can run its course, what happens to a person is never only an accident, and the reasons are beyond us.
One thing is not in dispute. The Mishnah (the core text of the Oral Torah) rules that on lightning, thunder and strong winds a person says a blessing: "Blessed is He whose strength and power fill the world." The words of that blessing are about power. They say nothing about who deserved what.
Radak, Rashi, Meiri and Malbim on Tehillim 148:8,Chagigah 12b,Rambam, Guide for the Perplexed 3:17 (Ibn Tibbon's Hebrew),Mishnah Berakhot 9:2"Young men and also young women." Why "also," as if girls come second?
Verse 12 is the one about your age group: "Young men and also young women, old people with the young." Two pairs, and two different joining words. Boys "and also" girls. Old "with" young. The commentators asked about both.
Radak (Rabbi David Kimchi, Provence, around 1200) explains "also" this way: young women are usually busy only with adorning themselves, so the verse says that they too will give praise to God. That is what he wrote. It is one reading, and the other commentators here read the word differently.
Ibn Ezra (a Spanish commentator who died in the 1160s) gives a simpler reason for the pair. People are male and female, he says, so the psalm names both. The males also change with time, their strength growing and then fading, so it names old and young. Malbim (a rabbi and commentator of the 1800s) is shorter still: the verse means males and females, big and small. Meiri (Rabbi Menachem Meiri, Provence, around 1300): it is the whole crowd together, of every nation.
Sefer Chasidim (a book of piety and custom from medieval Germany) looks at the word the verse did not use. It does not say young men "with" young women, the way it says old "with" young. So "also," it says, comes to include the women on their own. The book brings this verse as support for its rule against mixing boys and girls: each group praises on its own. Old and young praise together.
And why "with" for the old and the young? Radak: the old will teach the young how to praise, because the young do not know how on their own. Midrash Tehillim (a collection of rabbinic teachings on Tehillim) reads the two words as one group: old people who are young, the ones whose strength keeps being renewed.
The readings differ on the small words. None of them reads the verse as leaving anyone out. It is the one line in the psalm that names girls and names the young, and every reading above has them praising.
Radak, Ibn Ezra, Malbim and Meiri on Tehillim 148:12,Sefer Chasidim 168,Midrash Tehillim, on Tehillim 148:12