After the great flood reached its peak, a steady, daily decline in the water level began [רד״ק, שד״ל, ביאור יש״ר]. Noah could track this continuous drop simply by observing how the Ark settled lower each day [מלבי״ם]. Even as the overall water level decreased, some currents continued to flow and shift while others diminished [אור החיים]. The Ark's settling on solid ground and the later appearance of dry land did not happen simultaneously. The Ark was incredibly heavy, burdened with humans, countless animals, and massive food supplies, causing it to sit deep in the water. As long as the waters sprang from the depths and boiled, the Ark remained afloat. However, the moment the underground springs calmed, the immense weight of the Ark caused it to sink immediately and rest firmly on the mountain, long before the surrounding peaks emerged [רמב״ן, הטור הארוך, ביאור שטיינזלץ].
The exact timing of these events is a subject of broad discussion, specifically regarding the identity of the tenth month. The primary approach among commentators is that this refers to the month of Av, which is the tenth month when counting from Marcheshvan, the time the rains originally began [רש״י, מזרחי, גור אריה, שפתי חכמים]. Others suggest it was the month of Shevat, counting ten months from Iyar when the floodwaters first erupted [אבן עזרא, מחוקקי יהודה]. A third view holds that it was Tammuz, following the standard calendar year that begins with Tishrei [רמב״ן, ביאור יש״ר]. Regardless of the exact month, this date marks a major milestone in the drying of the earth, though the waters continued to recede long afterward [קאסוטו].
Eventually, the mountain peaks finally broke through the surface of the water. This gradual uncovering of dry land serves as a powerful parallel to the original creation of the world [קאסוטו]. Whether these were the absolute highest peaks [רד״ק] or simply mountains lower than the Ararat range where the Ark had already rested [שד״ל], they were the first signs of earth visible to Noah. This sighting was entirely based on Noah's limited vantage point from within the Ark; it is quite possible that land in more distant regions had already been exposed earlier [ביאור יש״ר].
Once the mountains were visible, Noah waited an additional forty days before opening the window. He reasoned that this period would be long enough for trees and tall structures to emerge, finally providing the birds with suitable places to nest [רמב״ן, הטור הארוך]. In his efforts to test the earth's condition, Noah applied his knowledge of astronomy. He sent the birds out in seven-day cycles, corresponding to the phases of the moon that influence the movement of water [אבן עזרא, מחוקקי יהודה]. He initially chose the raven, a bird known to fly high despite its lazy nature. Noah hoped the raven would fly to the newly exposed mountain peaks and remain there, thereby easing his heavy burden of caring for the animals. When the raven failed to find rest and merely flew back and forth, Noah changed his strategy. He sent out the dove, a diligent bird known for returning to its nest, making it the perfect scout to accurately determine if the waters had receded enough to find a resting place [מחוקקי יהודה].