Darkened
“12 And the fourth angel sounded, and the third part of the sun was smitten, and the third part of the moon, and the third part of the stars; so as the third part of them was darkened, and the day shone not for a third part of it, and the night likewise.”
(Rev 8:12 KJV)
This judgment can be taken several ways, which makes it difficult to understand the devastation that it could cause. It could be that the sun, moon, and stars are visible for one third less time than normal. It could be that their light is one third less bright than normal. This will most likely damage crops, and in turn harming` the food supply.
The Coming Trumpets
13 And I beheld, and heard an angel flying through the midst of heaven, saying with a loud voice, Woe, woe, woe, to the inhabiters of the earth by reason of the other voices of the trumpet of the three angels, which are yet to sound!”
(Rev 8:13 KJV)
An angel is warning the inhabitants of the earth and pronouncing woes upon them about the coming trumpets. These trumpets will be much worse than those that came before them. The devastation and judgment upon the earth is getting worse as the Great Tribulation continues.