Natural “Coldness” Facts
1. The refrigerator leads to a dramatic variation of temperature within such a small range in a single household.
If we dive into the temperature differences from indoor to outdoor, from underground soil to above ground surface around the whole year, In summer it keeps the heat outside while the underground soil temperature is relatively low. In winter it creates a cooling box inside a warm environment while there are great resources for refrigeration outside the house.
2. Modern appliances such as the humble fridge are nowadays taken for granted, yet fridges only became generally available for household use in the 1920s, which is really not that long ago. Before then, fresh meat and other food were usually preserved by storing with salt in a process that worked reasonably well. Few people had access to cold storage or to ice for drinks in summer. Apart, that is, from the wealthy who could afford to build and maintain an ingenious bit of kit to ease their lives: an ice house, or in some cases, multiple ice houses, innovative structures devised long before modern refrigerator.