Why does the coldest part of the winter come one month after the shortest day of the year?
It s mainly because it takes time for the atmosphere to adjust to the decreased amount of solar energy that occurs in the winter. This atmospheric lag is due to the huge volume of water in the oceans, which cover 71% of the Earth s surface and are a major contributor of energy to the atmosphere. Less solar energy in winter slowly lowers the temperature of water in the oceans, which in turn slowly cools the atmosphere. This is the reason for the temperature lag in winter, as well as during the summer, when the warmest weather occurs several weeks after the longest day. For a real-life example that explains the summertime lag, turn on a stove and feel over the burner the air is heated almost immediately (analogous to land on long, sunny days near the summer solstice). Put a pot of water over the heat, however, and the air above the water is not nearly as warm as it was before. It takes more energy to increase the temperature of water, which in turn warms the air above the water. To learn
