Nature has a rhythm. The occurrence of seasonal events like the unfolding of leaves in the spring, the blooming of flowers, the migration of birds and other biological events that reoccur with the passage of the seasons are influenced by an interaction of light, temperature and moisture.

The study of nature's rhythm is called phenology. Phenology is the study of how climate and the season's affect natural events.

The roots of phenology are in agriculture (excuse the pun), for instance, one important use is in pest control. Being able to predict the appearance of a pest is extremely valuable to farmers.

Hopkin's Law of Bioclimatics

Andrew Delmar Hopkins was the leading forest entomologist during the first part of the 20th century. Most of his work was done in Virginia and West Virginia. Andrew Hopkins first formulated the relationship of elevation, latitude and longitude to seasonal events like the coming of spring.

The relationship is one day for every 15 minutes of latitude, 1.25 days for each degree of longitude and one day for every 30 meters of elevation.

It seems that in North America the further west, or north, or higher, the later spring arrives. The effects of elevation, for example, are caused by a general lowering of temperature as temperature increases. Horticulturalist and gardeners around the world are quite familiar with these natural timings repeated annually.

Here are some details on Hopkins Law of Bioclimatics

1. For every ¼ degree (15 minutes of latitude) you travel North, there is a 1 day delay for the coming of spring.
2. For every degree of longitude you travel West, there is a 1 ¼ day delay for the coming of spring.
3. For every 100 feet you travel up in elevation, there is a 1 ¼ day delay for the coming of spring.
*****Note.... While some latitude and longitude notations use negative numbers to represent western longitudes and southern latitudes, you should always use POSITIVE NUMBERS.*****

Example Calcuations using Hopkins Law:
If you were to travel from Kansas City(1000 ft elevation, 39.11 degrees N latitude, -94.63 longitude) to Omaha, Nebraska(1034 feet elevation, 41.26 degrees N latitude, -95.93 longitude), the delay in the coming of spring would be…

The way the living world reaches to the seasons can serve as valuable indicators of both the health of the environment. It has been suggested (Schwartz, 1994, 1998) that changes in phenologic timing may serve as a possible measure of climatic change. One ongoing project has mapped the blooming of cloned lilac bushes, other phenology projects have been going on for over 40 years.

Related Link: "A Time for Every Purpose Under Heaven" by Gregory K. Scott