What is the drawback to use period of pendulum as time standard

The time period of a simple pendulum depends upon its length and value of'g'at any place. The period of the pendulum of fixed length

a high pressure system is a dense air mass that is usually cooler and drier than the surrounding air. a low pressure system is a less dense air mass that is usually wetter and warmer than the surrounding air.

in general, areas that experience high atmospheric pressure also experience fair weather. low pressure systems can cause the formation of clouds and storms. air usually flows from areas of high pressure to areas of low pressure..