one of the three basic phases of matter; a gas can expand indefinitely to completely fill its container
the typical atmospheric weather patterns over the earth
the height above sea level of a pressure level. For example, if a station reports that the 500 mb height at its location is 5600 m, it means that the level of the atmosphere over that station at which pressure is 500 mb is 5600 m above sea level. This value varies and is estimated based on temperature and pressure data.
a theoretical wind that results from the balance between the horizontal pressure gradient force and the Coriolis force. It is assumed to be straight-line, frictionless flow (which is more likely to be found at higher levels in the atmosphere). In the Northern Hemisphere, low pressure is found to the left of the flow of the geostrophic wind, while in the Southern Hemisphere, low pressure is found to the right of the flow.
a term applied to any equatorial satellite that is virtually motionless with respect to an observer on the ground. This satellite has an orbital velocity equal to the rotational velocity of the earth.
see Ground Fog
the condition that exists when land is covered with glaciers
a large body of ice moving slowly down a slope or valley or spreading outward on a land surface
the largest scale of planetary motion; covering all or most of a latitude circle
the increase in the average measured temperature of the Earth’s near-surface air and oceans since the mid-20th century and the projected continuation. It is an enhancement of the Greenhouse Effect and usually refers to human-induced changes.
an optical effect characterized by concentric rings of color (red outermost and violet innermost) surrounding the shadow of an observer’s head when the shadow is cast onto a cloud deck below the observer’s elevation. A glory can also be seen sometimes around a plane when it is flying above clouds.
in general, the spatial change of a physical quantity (e.g., temperature). A strong gradient means that the quantity changes rapidly as you move from one side of the gradient to the other. For example, a strong temperature gradient (lots of isotherms packed together) could mean that as you walk from one side to the other, the temperature will change rapidly. A weak gradient (isotherms spaced out) means that the quantity changes more gradually.
in particular, the force imparted by the earth that tends to draw all bodies in the earth’s sphere of influence toward the center of the earth
a hypothetical "body" that absorbs some constant fraction of all electromagnetic radiation incident upon it
a pattern of radar echoes from fixed ground targets (buildings, hills, etc.) near the radar. This contamination is processed into the NEXRAD base products (base reflectivity, base velocity, and spectrum width) and affects all derived products. Ground clutter is most prevalent close to the radar at the lowest elevation slices. Ground clutter is always present around the radar and is not the same as anomalous propagation (AP), which occurs during certain atmospheric conditions.
the current that moves along the ground from the point where a direct stroke of lightning hits the ground.
a form of degree-day used as a guide to determine the most appropriate time to plant and harvest crops
a warm, swift, relatively narrow ocean current that flows along the east coast of the United States