A helpful glossary of terms associated with weather and climate.

# A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Radar data

Precipitation recorded by a radar across an area, which measures the reflectivity of rain drops before they hit the ground.

Rain gauge

A device for measuring the amount of precipitation (rain and snow) at a specific point over a period.


The process of applying modern data assimilation techniques to historical periods. A consistent scheme is applied to periods of decades (for climate monitoring and associated products) or longer (for climate change studies). Reanalyses are important since they provide weather and climate information across the region, not just where there are observations. They give a more complete and coherent picture of the weather than can be obtained from observation data alone.


climate models split the Earth's atmosphere and ocean into a finite number of grid boxes (similar to the pixels on a digital camera) - the higher the number of grid boxes, the higher (or finer) the spatial resolution. For example, a model with a horizontal resolution of 1 degree would have 360 (latitude) x 180 (longitude) = 64,800 grid boxes. The height of the atmosphere, and the depth of the ocean are split into distinct layers - so the number of these layers determines the vertical resolution of the model.