If a lightning strike is a sufficient distance from the observer, sound from the strike will not be heard. These silent bolts are called heat lightning. Lightning bolts produce thunder, but the thunder sound does not travel all the way to the observer if the observer is too far away. The movement of sound in the atmosphere depends on the atmospheric properties of the air such as temperature and density.
Collagen vascular diseases are autoimmune diseases that affect connective tissues, and occur when the bodyâs immune system attacks its own tissues and organs. Lupus is often characterized by a facial rash on both cheeks. Lupus patients may experience fatigue, joint pain, skin lesions and shortness of breath.
Inflammatory bowel disease symptoms vary, depending on the severity of inflammation and where it occurs. Symptoms may range from mild to severe. You are likely to have periods of active illness followed by periods of remission. Signs and symptoms that are common to both Crohn's disease and ulcerative colitis include:1  Diarrhea. 2  Diarrhea is a common problem for people with IBD. 3  Fever and fatigue. 4  Many people with IBD experience a low-grade fever. 5  You may also feel tired or have low energy. 6  Abdominal pain and cramping.ou are likely to have periods of active illness followed by periods of remission. Signs and symptoms that are common to both Crohn's disease and ulcerative colitis include: 1  Diarrhea. 2  Diarrhea is a common problem for people with IBD.