| A | B |
|---|
| time heat flow into air is greatest | noon |
| As the percentage of greenhouse gases increases ... | ... heat flow out of Earth’s air decreases |
| Greenhouse gases | block flow of heat out of Earth’s air |
| time heat flow into air is lowest | nighy or cloudy weather |
| As the percentage of greenhouse gases decreases... | ... heat flow out of Earth’s air increases |
| If the greenhouse gases were not present... | ... heat would radiate into space instead |
| time surface temperature highest | 4:30 pm |
| Global warming is caused by | greenhouse gases |
| one greenhouse gas is | carbon dioxide |
| time surface temperature lowest | 7 am |
