Strong Wind

When the water flow speed is high and the pressure is low, when the wind blows across the lake, a pressure difference is created at the original balance, and the lake water will be "sucked up", and then under the pressure in the horizontal direction, a horizontal velocity will be generated.

Tides

• When swimming at the beach, you must pay attention to the time of rising and falling tides. Otherwise, once you encounter high tide or low tide in the sea, and if you fail to do the relevant prevention work, it is easy to appear some dangers from large to small, and it may be possible. There is no continental shelf.
• Need to pay attention to the currents under the sea. In some areas, the ocean current is rapid, or the ocean current route is irregular. It is best not to go to such a place.
• Swimming in the sea at low tide is very dangerous. The retreating sea water can easily bring people deeper into the sea, so swimmingat low tide is not recommended. Compared to swimming at high tide, swimming at low tide is more dangerous.

Source from https://www.theswimguide.org/2020/02/19/everything-you-need-to-know-about-tides/Links to an external site..

Sea Fog

• The sea suddenly fogged up, and in a flash, the waves and floats not far away could not be seen. This is a major feature of sea fog. You can get up quickly and you can hide everything within a few minutes. It is very easy to get accidents if you are stuck in thick fog and don’t know the direction.
• When we are swimming, we also should pay attention to advection fog. It is the warm air on the ocean passing through the cold sea surface. As the temperature of the warm air decreases, the water vapor contained in it becomes saturated, and then fog occurs. This kind of fog is the result of the horizontal flow of air, so it is called advection fog. Because it mostly occurs on the sea, it is also called sea fog.

Wind Waves and Swells

• Irregular waves formed by wind and waves, including residual waves and breaking waves, have more complicated effects on swimming. Because of its regular and smooth characteristics, the swell has a relatively direct impact on sea swimming.
• Wind waves of varying lengths and heights appear in the wind and waves at the same time, the wave surface is relatively steep, and there are waves or large patches of foam near the wave crests, one after another.
• Swells refers to the waves that come down after the wind stops or in the sudden change of wind speed and direction, and the waves from the outgoing wind area. Its basic characteristics are: a relatively regular shape, neat arrangement, smooth wave surface, and long wave crest line.

Source from https://www.outdoorswimmingsociety.com/weatherproof-your-swimming-understanding-swell/Links to an external site..

Thunderstorms

Whether it’s a weather forecast of a thunderstorm or a swimming, you hear the thunder, it means that the lightning is not far away from you. If the lightning falls into the water, people and water are conductors, and the average resistance of the organs and tissues in the body is 700 ohms. The greater the resistance, the more serious the consequences. Once the human body is struck by lightning in the water, it will be shocked and cause drowning without direct death. When there is a thunderstorm, you should leave the waters (reservoirs, ponds, outdoor swimming pools, lakes) immediately, leave like lightning, and take refuge in a dry environment.

Sun

Swimming in the sun will have a double load. One is direct exposure to the sun without protection, and the other is the reflection of the water surface. The intensity of the reflection of the water surface is not much less than that of the direct sunlight.

Sea water contains salt. When the sun's altitude angle is the largest at noon, coupled with strong ultraviolet rays. Our skin is usually protected very well and suddenly can't stand the irritation.

Snow

Winter swimming is an exercise performed when the temperature is low. It is easy to catch a cold. In severe cases, viral myocarditis may also occur. To avoid such physical injury, you should insist on rubbing your body with cold water every morning and evening to allow your body to adapt to the cold water, promote blood circulation throughout the body, and improve the resistance of the nasal mucosa to cold stimulation exercises.