Hail is solid ice precipitation formed when water droplets freeze and grow within strong thunderstorm updrafts until they become too heavy and fall to the ground. Understanding hail size is important for assessing potential damage to vehicles and roofs.
Understanding Hail Size and Damage Potential
Hailstones are typically measured by their diameter and are often compared to common objects for easier understanding. Pea-sized hail, approximately 0.25 inches (0.64 cm) in diameter, generally causes minimal damage, perhaps only minor scuffing or dings to soft metals. Marble-sized hail, around 0.5 inches (1.27 cm), might lead to minor surface-level damage on shingles, potentially initiating granule loss. When hail reaches the size of a dime or nickel, about 0.75 to 0.88 inches (1.9 to 2.2 cm), it can cause more significant granule loss on shingles and dents in soft metals.
Quarter-sized hail, measuring 1 inch (2.54 cm) in diameter, is large enough to cause damage to roofs, siding, and windows. This size of hail can prompt the need for professional inspection due to potential shingle fractures and dents in metal roofs. Golf ball-sized hail, at 1.75 inches (4.45 cm), is highly destructive, capable of extensive damage to vehicles, shattering windows, and causing severe roof and structural harm. Hailstones larger than 2 inches (5.08 cm), such as tennis ball-sized (2.5 inches or 6.35 cm) or baseball-sized (2.75 inches or 6.99 cm), can inflict major structural damage, including punctures in roof decking.
Common Types of Hail Damage
Hail can inflict a range of specific damage to property, impacting both vehicles and structures. For vehicles, common hail damage includes dents and dings on the exterior body panels, which can range from small cosmetic blemishes to larger, noticeable indentations. High-speed hail impacts can also chip or crack a vehicle’s paint, exposing the underlying metal and increasing the risk of rust and corrosion. Windshields and other glass components, like side and rear windows, are vulnerable to cracking or shattering, posing both a safety and visibility hazard.
Roofs often bear the brunt of hailstorms, experiencing several distinct types of damage. Asphalt shingles can suffer from granule loss, where the protective mineral granules are dislodged, exposing the underlying asphalt mat to ultraviolet (UV) radiation and accelerating wear. Hail impacts can also lead to shingle bruising, cracking, or splitting, which compromises the shingle’s integrity and can result in leaks. Beyond shingles, hail can cause dents and deformation on metal roofs, flashing, and vents, while tile roofs may experience visible cracks or shattered sections.
Factors Influencing Damage Severity
While hail size is a primary factor, several other variables significantly influence the extent of damage. Wind speed and direction play a substantial role, as strong winds can increase the impact force of hailstones and cause them to strike at a steeper angle. This angled impact can amplify peak forces by nearly 19% compared to windless conditions, leading to more concentrated and deeper dents. Wind-driven hail can also tear up siding on houses and break windows, affecting areas beyond just the roof.
The density and hardness of hailstones also affect damage potential. Hailstones with greater density, closer to that of pure ice, possess more kinetic energy upon impact, increasing their ability to dislodge granules, dent metal, or fracture brittle materials. Softer, less dense hailstones, which may contain more air bubbles, are generally less destructive but can still leave temporary marks or spatter. The duration of a hailstorm directly correlates with the amount of damage; longer storms mean more impacts and a greater likelihood of cumulative damage. Different materials also exhibit varying susceptibility; older or less impact-resistant roofing materials and thinner car panels are more prone to damage than newer, more robust alternatives.
Responding to Hail Threats
Taking proactive steps before a hailstorm can help mitigate potential damage. When severe weather is anticipated, it is advisable to move vehicles into a garage or covered area to shield them from direct impact. Outdoor items such as patio furniture, grills, and other accessories should be secured or brought indoors to prevent them from becoming projectiles or sustaining damage. Clearing eavestroughs of debris can also help ensure proper drainage and minimize water damage if heavy rain accompanies the hail.
During a hailstorm, safety indoors is paramount. It is important to stay inside a secure building and remain away from windows, glass doors, and skylights to avoid injury from shattered glass. Closing drapes or blinds can provide an additional layer of protection against flying debris. If caught driving during a hailstorm, it is safest to pull over to a secure location, such as a covered parking garage or under a service station awning, if accessible. If no shelter is available, angling the vehicle so hail strikes the reinforced windshield rather than side windows can offer better protection.
After the storm passes, safely assessing any damage is the next step. Once the hail has stopped and it is safe to go outside, carefully inspect your property for signs of impact on vehicles, roofs, and other exposed areas. Documenting any damage with photographs or videos can be helpful for insurance purposes.