There are four important warning signs that should prompt you to talk to a health care provider. 1  Pain. Pain from arthritis can be constant or it may come and go. 2  Swelling. Some types of arthritis cause the skin over the affected joint to become red and swollen, feeling warm to the touch. 3  Stiffness.
There's a whole lot of water on Earth! Something like 326,000,000,000,000,000,000 gallons (326 million trillion gallons) of the stuff (roughly 1,260,000,000,000,000,000,000 liters) can be found on our planet. This water is in a constant cycle -- it evaporates from the ocean, travels through the air, rains down on the land and then flows back to the ocean.
How much water is that? It's roughly 326 million cubic miles (1.332 billion cubic kilometers), according to a recent study from the U.S. Geological Survey. Some 72 percent of Earth is covered in water, but 97 percent of that is salty ocean water and not suitable for drinking. There's not a lot of water on Earth at all, said David Gallo, an oceanographer at the Woods Hole Oceanographic Institution (WHOI) in Massachusetts. Oceans create a water layer spanning 15,000 miles (24,000 kilometers) across the planet at an average depth of more than 2 miles (3.2 km).