Of those, 47 reach strength higher than 119 km/h (74 mph), and 20 become intense tropical cyclones (at least Category 3 intensity on the Saffir–Simpson scale).Climate cycles such as ENSO and the Madden–Julian oscillation modulate the timing and frequency of tropical cyclone development. Rossby waves can aid in the formation of a new tropical cyclone by disseminating the energy of an existing, mature storm. Kelvin waves can contribute to tropical cyclone formation by regulating the development of the westerlies. Cyclone formation is usually reduced 3 days prior to the waves crest and increased during the 3 days after. Rapid intensification
On occasion, tropical cyclones may undergo a process known as rapid intensification, a period in which the maximum sustained winds of a tropical cyclone increase by 30 kn (56 km/h; 35 mph) or more within 24 hours. Similarly, rapid deepening in tropical cyclones is defined as a minimum sea surface pressure decrease of 1.75 hPa (0.052 inHg) per hour or 42 hPa (1.2 inHg) within a 24-hour period; explosive deepening occurs when the surface pressure decreases by 2.5 hPa (0.074 inHg) per hour for at least 12 hours or 5 hPa (0.15 inHg) per hour for at least 6 hours. For rapid intensification to occur, several conditions must be in place. Water temperatures must be extremely high (near or above 30 °C (86 °F)), and water of this temperature must be sufficiently deep such that waves do not upwell cooler waters to the surface.
Siderosis is the deposition of excess iron in body tissue. When used without qualification, it usually refers to an environmental disease of the lung, also known more specifically as pulmonary siderosis or Welders disease, which is a form of pneumoconiosis. Pulmonary siderosis was first described in 1936 from X-ray images of the lungs of arc welders.The name siderosis comes from Ancient Greek word for iron, sídēr(os), and has an -osis suffix. Signs and symptoms
Pulmonary siderosis doesnt usually cause harmful scar tissue formation within the lungs, which is why it said to be non-fibrotic condition, unlike asbestosis for example, and has also been called "benign pneumoconiosis".Mild to moderate scarring of the lungs has been found in unusual cases of pulmonary siderosis. These people have had persistent breathlessness, coughing and decreased lung function. However, people in occupations where they are exposed to iron (or rust) dust are usually also exposed to other forms of dust such as silica, which upon repeated inhalation is known to cause dangerous silicosis. Because of this, it is not known for certain whether the inhalation of pure iron or rust can cause detrimental scarring of the lungs that has been seen in some cases of pulmonary siderosis. Still, studies have shown lack of silica in tissue samples collected from people with pulmonary siderosis.