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TEMPERATURE |
PRESSURE |
WIND DIRECTION |
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DEWPOINT |
PRECIP RATE -- mm/hr |
WIND & GUST -- / -- km/h |
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HUMIDITY |
PRECIP ACCUM |
UV/Solar Radiation -- / -- |
CURRENT CONDITIONS
Location
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The most basic change in pressure is the twice daily rise and fall in due to the heating from the sun. Each day, around 4 a.m./p.m. the pressure is at its lowest and near its peak around 10 a.m./p.m. The magnitude of the daily cycle is greatest near the equator decreasing toward the poles.
On top of the daily fluctuations are the larger pressure changes as a result of the migrating weather systems. These weather systems are identified by the red H's and blue L's seen on weather maps.
In weather forecasts, low pressure regions tend to have bad weather and high pressure regions tend to have good weather. When the pressure is low, the air is free to rise into the atmosphere, so it has to suck in air from the surroundings. When air rises, it expands and cools off. If there is enough water content, then the water can condense and form rain.