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| Avogadro's number, 6e23, is the number of hydrogens in a gram, so the solar wind is about 3 micrograms per square kilometer per second (again, at Earth's solar radius). The Sun facing area of the Earth is the polar radius (6357km) times the equatorial radius (6378km) times pi, around 1.3e8 km², so (ignoring Earth's magnetic field) the mass of hydrogen intersecting the '''Entire Earth''' per second is around 400 grams per second, or 0.4 kg/s, a bit less than a pound per second. | Avogadro's number, 6e23, is the number of hydrogens in a gram, so the solar wind is about 3 micrograms per square kilometer per second (again, at Earth's solar radius). The Sun facing area of the Earth is the polar radius (6357km) times the equatorial radius (6378km) times pi, around 1.3e8 km², so (ignoring Earth's magnetic field) the mass of hydrogen intersecting the '''entire Earth''' per second is around 400 grams per second, or 0.4 kg/s, a bit less than a pound per second. |
Heliotosis
The so-called solar wind
The solar "wind" is absurdly thin. At the Earth's radius from the Sun, about 4 hydrogens per cubic centimeter, or 4 million hydrogens per cubic meter. It moves fast, perhaps 500 km/s, so that 2e12 hydrogens pass through a square meter per second, or 2e18 hydrogens pass through a square kilometer.
Avogadro's number, 6e23, is the number of hydrogens in a gram, so the solar wind is about 3 micrograms per square kilometer per second (again, at Earth's solar radius). The Sun facing area of the Earth is the polar radius (6357km) times the equatorial radius (6378km) times pi, around 1.3e8 km², so (ignoring Earth's magnetic field) the mass of hydrogen intersecting the entire Earth per second is around 400 grams per second, or 0.4 kg/s, a bit less than a pound per second.
A typical weather balloon is a meter in diameter, about 4 cubic meters, 4000 liters. Hydrogen gas at STP is 0.09 g/L, so a slightly pressurized weather balloon also holds about 0.4 kilograms. Worldwide, perhaps 900 weather stations launch two balloons per day, so the solar wind delivers 50 times that amount.
- Actually, some weather balloons are filled with irreplaceable helium, because hydrogen is flammable, as are some of the places (like college campuses) where the balloons are launched.