Page 46 - COPA_July2023

PILOT POINTERS
Sea breeze circulations can bring rain and storms to coastal airports daily. They are created as solar heating raises the land temperature during the day, producing an inland airflow and rising, humid air over the land. The process may reverse at night when the land becomes cooler than the adjacent water.
along the boundary between the onshore flow and the warmer air being displaced upward. As solar input wanes toward sunset, the circulation contracts and the front retreats toward the coast. Overnight, the sea breeze front may be several miles offshore, awaiting the next sunrise.
Although sea breeze fronts are common in warmer latitudes, they can exist along any coastline where the difference between land and sea temperatures is large, and the water is warm enough to support high humidity throughout the troposphere. Most sea breeze fronts, however, will appear only as a wind shift and some cumuli. Fortunately, sea breeze fronts are predictable. With slight variation throughout the year as the solar angle changes, the front can be expected to move over the same areas at around the same time each day – usually once in the morning moving inland, and once in the afternoon moving seaward.
Fog
Many airports are situated on the coast because it often provides sufficient flat land that may not be suitable for other development. In some places, coastal airports have even been built on offshore fill. This geography can cause several weather headaches for aviators. These airports can be especially susceptible to advection fog. Advection fog, the kind of fog places like San Francisco are famous for, is produced when warm, humid air moves over a cold surface and the surface cools the air to saturation. This is common along the west coasts of most continents where cold ocean currents suppress water temperatures. When atmospheric pat- terns introduce a shoreward flow of air from over warmer waters and this air must pass over the cold water near the coast, the air chills and creates an onshore fog that can persist for several days.
44 JULY 2023 COPA Pilot
CREDIT: KARSTEN SHEIN