Which step(s) of the greenhouse effect are being most affected by the increases in greenhouse gases, leading to an increase in heat? 1. Solar radiation enters the Earth system and is reflected and absorbed. 2. Absorbed energy is released into the atmosphere as heat. 3. Heat is absorbed by the atmosphere. 4. The atmosphere re-releases heat, warming Earth's surface and lower atmosphere. 1 and 2 2, 3 and 4 1, 2, and 3 3 and 4

Agroup of students is studying convection current. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other is in an area with warm air. after 10 minutes, the balloon are released from a height of 1 meter. which of the following to the students most likely observe? a) the warm balloon expands and rises. the cold balloon shrinks and sinks b) the balloon both rise. the cold balloon is larger than the warm balloon c) the cold balloon expands and rises. the warm balloon shrinks and sinks d) the balloon rise at the same rate. both balloons are the same size