As an illustration if we call "20m above sea level" the normal altitude of Australian humans ( majority living in coastal capital cities) then when you go for a flight on a CO2 spewing qantas jet to Paris for a climate conference and you are served your meal your altitude is a positive anomaly, when you descend rapidly for landing your rate of change of altitude is negative but your altitude is still a positive anomaly while you are still above reference normal. If you stepped on a landmine on the beach at waters edge and were thrown rapidly into the air 10m then your altitude would be a negative anomaly but the rate of change would be positive as you ascended.
