Weather, Waves and Tides
If you want to catch the surf at its best, it’s essential to know about the weather. Many surfers are obsessed with the weather, always aware of the latest and most accurate predictions. Whilst you don’t need to become a forecast junkie, it’s good to have a basic understanding of weather and swell.
·Low pressure systems (usually marked with a big LOW or L on weather charts) are storm systems that generate swell. High pressure systems (marked with a big HIGH!) bring good weather but don’t usually generate swell.
·Swell is produced when the fast moving surface air of a low pressure system generates disturbance as it blows over the surface of the sea.
·Once the sea surface is rippled, swell will grow, provided the wind continues to blow.
·When swell is produced by a low pressure system it starts to travel.
·When the swell arrives at the coast the shallower water will cause it to “jack up” and form a breaking wave.
Types of Waves
The type of wave created will depend on the bottom contour of the area you’re surfing. There are three main types of wave: beach break, reef break and point break.
Beach break- Waves break onto a sandy bottom, which can be shallow or steep shelving.
Reef- Waves break over rock, producing a fast steep hollow wave.
Point- Waves break off a point of land that projects into the sea, causing the waves to wrap around and break along it.
Sussing what the wind is doing is an important factor in determining good surf. Good surfing conditions occur when swell is combined with offshore winds (winds blowing from the land to the sea). This cleans the swell and grooms the waves. Poor surfing conditions occur when swell is combined with onshore winds (wind blowing from the sea to the land) Onshores cause the waves to be mesy and of poor quality and as a consequences bad for surfing. Check the wind direction nd strength when planning a surf.
When surfing it’s important to understand how changing tides affect a break. Most surf spots seem to break best at a preferred tide and changing tides can change the shape of waves (causing them to dump or not break at all) or can introduce new hazards to the lineup.
Most surf shops sell annual tide tables (with info on the tide times for different areas year round) so that surfers can keep up to date. Talk to a local surfer at your chosen surf spot, to find out what tides it works best at.
·Tides are produced by a gravitational pull of the sun and moon on the earth.
·In Ireland, we have two tides a day (semi-diurnal), the sea reaches its highest level twice a day with an average interval of 12 hours and 25 minutes.
·This means that the tide is around fifty minutes later every day. So, if the tide is high at 6pm this evening it will be high at 6.50pm tomorrow evening.
·Tides are also affected by a spring neap cycle that causes the tidal range to change. A spring high tide is much higher than a neap high tide and a spring low tide is much lower than a neap low tide.
·Spring tides occur just after the full moon, then again approximately two weeks later, just after the new moon. Smaller neap tides occur after the half moon.