atop -a | Display only active processes
atop -g | Display general process info
atop -m | Display memory usage info
atop -n | Display network usage info
atop -d | Display Dick usage info

Alternatively you can just use atop and then key in the letters above to switch between.

atop -r | read raw data.

Use this to basically start looking at the processes from the start of the day 00:00

atop -r -b 09:00    | read raw data from 09:00 today
atop -r y           | read raw data from yesterday
atop -r yy          | read raw data from the day before yesterday
atop -r y -b 09:00  | read raw data from 09:00 yesterday
atop -r yy -b 09:00 | read raw data from 09:00 the day before yesterday
atop -r <log>       | read data from a log stored in /var/log/atop