Hail is precipitation consisting of solid ice originating within the strong updrafts of severe thunderstorms. Hail size is often reported by comparing the frozen chunks to common objects. This provides a quick, understandable reference point for the public and meteorologists. This method allows for rapid communication about the potential threat a storm poses. The size referred to as “quarter size” is a significant benchmark in weather reporting.
The Official Measurement of Quarter Size Hail
The official, standardized diameter for “quarter size” hail is \(1.00\) inch (\(2.54\) centimeters). This measurement serves as a critical threshold in meteorology. The \(1.00\)-inch diameter is the minimum size required for a thunderstorm to be officially classified as “severe” by the National Weather Service (NWS) in the United States.
This standard was updated around 2010, raising the threshold from the previous standard of \(0.75\)-inch hail (roughly the size of a penny). The change occurred because research indicated that hail smaller than one inch rarely caused widespread property damage. Classifying storms with hail one inch or larger as severe ensures that warnings are issued for events with a genuine potential for destruction.
The Practice of Using Common Object Comparisons
Meteorologists rely on common object comparisons because they offer a consistent, universally recognizable way to communicate hail size quickly. Since the public often reports the size of falling hail first, using an everyday object like a coin eliminates the need for precise measuring tools. The quarter is ideal because its standardized size makes it a reliable reference for the one-inch severe weather threshold.
Other objects are used to communicate sizes smaller or larger than a quarter.
Common Hail Size Comparisons
- Pea (approximately \(0.25\) inches)
- Penny (about \(0.75\) inches)
- Nickel (close to \(0.88\) inches)
- Golf ball (\(1.75\) inches)
- Baseball (\(2.75\) inches)
Objects with variable sizes, such as a marble or a hen egg, are discouraged from use in official reporting to maintain consistency.
Assessing Damage Potential
Quarter-sized hail, at \(1.00\) inch in diameter, is capable of causing damage to vehicles and property. The force of impact is often enough to cause bruising to the shingle underlayment of a roof, even if the damage is not immediately visible. It can also result in dents and cracks in gutters, along with visible harm to siding.
The extent of the damage is determined by the hailstone size, its fall speed, and the wind accompanying the storm. Hailstones one to \(1.75\) inches in diameter typically fall between \(25\) and \(40\) miles per hour. When this velocity is combined with strong horizontal winds, the impact force increases significantly, potentially breaking windows or tearing up siding. Agriculture is particularly vulnerable, as a hailstorm of this magnitude can severely damage or destroy crops.