The important difference between the weeping and howling in verse 8 and the praise and thanksgiving of verse 10 is the intervening information that “the three days [did] pass away … and the earth did cease to tremble, and the rocks did cease to rend.” The terror of nature faded, and with the light of morning came the promise that life would return. While the people were still in darkness and amidst the destruction, their hearts were overcome with sadness.
The new day gave new hope. That the day came would have been seen as God’s promise to allow them to repent.