You spread a canopy over heaven to cover my Temple;In his commentary on the Kinot, Rav Joseph B. Soloveitchik OBM compares the above stich to a similar verse in Megillat Eicha: "You have covered Yourself with a cloud, so that no prayer can pass through." (3:44) The implication of these verses is that God has effectively shut the Jewish Nation out; He has not only enshrouded the physical location of his Presence in an opaque cloud to block the supplication of the Prophet, but has concealed Himself as well, as it were.
You concealed Yourself and vanquished my strongmen. - Rabbi Elazar HaKalir, Kinah 6
Rav Soloveitchik expands upon this idea as the fulfillment of the kabbalistic notion of hester panim (Divine concealment). Hester panim is the signal of a new low for the Jewish people - the Jews have reached a spiritual nadir wherein the Master of the World does not distinguish between the righteous and the wicked (Bava Kamma 60a). Essentially, hester panim is a fate far worse than the destruction of the Beis HaMikdash, as it symbolizes the converse of the Cloud of Glory, and the Cloud that descended upon Mount Sinai during the Divine Revelation. Those Clouds signified that the Presence of HaShem was among us, that we were worthy of the moniker "The Chosen Nation"; the paytan is lamenting the advent of a different sort of "cloud".
However, Rav Shimshon Pincus OBM presented a more positive element to this very theme.
He begins with a "novel" explanation about the nature of a mechitza, by reifying the very purpose of this structure. The common conception is that the mechitza is a barrier, something that is created into order to make a separation between people, to divide them. The truth is actually more sublime: the intent of the mechitza is not to separate, but rather to bring people closer. Halachically speaking, if there is no mechitza then men and women cannot be in the same room during prayer, or kriyat haTorah; with the presence of a mechitza, women are able to participate in the same services as the men. In this sense, the mechitza helps people achieve a closeness to God that is otherwise not possible, by bringing them into the prayer hall together with the congregation.
Similarly, when it seems like God is erecting something that separates us from Him, it is really serving the purpose of bringing us even closer to Him. The Cloud at Sinai was necessary for the Revelation; without it, we would never have been able to honor our rendezvous with our Creator! HaShem's glory is too great for us to bear without something "filtering" the splendor and luminescence.
Hester panim works along similar lines. The fact that God has shrouded himself in an impenetrable barrier of thick cloud is not meant to be a deterrent for our attempts to draw close. It is a sign that we must try harder, and that he wants us to strive to draw ever nearer to Him. Like a father who dresses up in a scary costume to frighten his children, the intended effect is that although the children are indeed scared by the horrid mask, they run into his outstretched arms!
Even in terrible moments of hester panim, in our darkest experiences of suffering and anguish, we must call out to Him in heartfelt prayer. Longing for the salvation, we beg with tearful eyes turned toward that very cloud, for we know that He is just on the other side, listening intently. The Gates of Prayer can sometimes be closed, but the Gates of Tears will never be locked.
Although the cloud seems to be thick, seems to be made of a unnatural density that swallows up sound entirely, it is not. Every prayer has immense power, and carries with it the capacity to break through the barrier, causing the rest of the cloud to dissipate like fog. This is true even in our generation, the Ikvisa d'Meshicha, when we are at our weakest; common sense would dictate that if our great predecessors were unable to bring the Redemption, then what can we possibly do?
Rav Moshe Weinberger likens this to the stronghold of a Kingdom that has successfully rebuffed numerous campaigns to infiltrate its fortress, led by some of the greatest military minds in the world. At one point, a small kingdom gathers its men and prepares to make an attempt on this bastion of security. Scoffers mock the men of this modest campaign - if the greatest armies could not prevail, then what chance do these civilian warriors have? But the general reassures his troops: according to his calculations, the previous onslaughts have seriously weakened the barricade of the fortress. With just one more strategic push, they can break through and overtake the city.
Tisha b'Av usually falls out on the week that we read Va'Eschanan, when Moshe relates his attempts to pray for a chance to enter the Holy Land. The commentaries explain that the word Va'Eschanan alludes to the 515 separate, distinct prayers that Moshe offered, pleading for God to allow him entry into Eretz Yisrael. They continue with the note that had Moshe offered just one more prayer, his request would have been granted. We must learn from this a most important lesson about our prayer - we can never know just how much is "enough", so we must always make an effort to pray, consistently and constantly.
HaShem is listening; our prayers can pierce the veil, and bring about the final redemption, so that this 9th of Av can be a real holiday.