what causes a tomato to ripen on the bottom and be yellow on the top

Question

My tomatoes are ripe on the bottom but the top third is yellow?

Answer 1

This is caused either be very bright, direct sun on the fruit or high temperatures. The heat, either from the air around the tomato or from the sun, causes the chlorophyll at the top of the fruit to be slower to break down, which keeps the shoulders of the fruit green or yellow.