Weather Overview: Tornados, Hurricanes, Precipitation, Floods, Etc

Humidity Humidity is the measure of the amount of water vapor in the air.

Relative Humidity… The percentage of water vapor that is actually in the air compared to the maximum amount of water vapor the air can hold at a specific temperature.

How is Relative Humidity Measured? It is measured with a psychrometer!

Precipitation… Precipitation is any form of water that falls from clouds and reaches Earth’s surface. Water evaporates from every water surface on earth and from living things. This water eventually returns to the surface as precipitation. Not all clouds produce precipitation. For it to fall, cloud droplets or ice crystals must grow heavy enough to fall through the air. One way that cloud droplets grow is by colliding and combining with other droplets. As they grow larger, they move faster and collect more small droplets. Finally, the droplets become heavy and fall out of the cloud as raindrops.

Types of Precipitation: Rain: The most common type. They must be at least 0.5 millimeters in diameter to be rain. Smaller than that means that it is mist. Sleet: Ice particles smaller than 5 millimeters in diameter. Freezing Rain: Falls as rain and freezes when it hits a cold surface. Snow: When water vapor in a cloud is converted directly into ice crystals. Hail: Round pellets of ice larger than 5 millimeters in diameter.

Floods.. A flood can be small or large and they all occur when the volume of water in a river increases so much that the river overflows its channel.

Flash Flood A sudden, violent flood that occurs within a few hours, or even minutes, of a storm.

Storms A storm is a violent disturbance in the atmosphere. They involve sudden changes in air pressure, which in turn cause rapid air movements. Conditions that can bring one kind of storm can also bring other types of storms in the same area.

Thunderstorms A thunderstorm is a small storm that is often accompanied by heavy precipitation and frequent thunder and lightning.

Lightning A sudden spark, or electrical discharge. As these charges jump between parts of a cloud, between near by clouds, or between a cloud and the ground. It is very similar to when you get shocked by someone with static electricity….Just on a much larger scale.

Thunder A lightning bolt can heat the air near it to as much as 30,000 degrees Celsius. This is much hotter than the surface of the sun!!! Thunder is the sound of the explosion. Because light travels much faster than sound, you see lightning before you hear thunder.

Tornado A tornado is a rapidly whirling, funnel-shaped cloud that reaches down from a storm cloud to touch Earth’s surface.

How Tornados Form… They are most likely to occur when thunderstorms are likely, in the spring and early summer. A warm air mass and a cold air mass meet. Once they meet, the cold mass moves under the warm air, forcing it to rise. A squall line of thunderstorms is likely to form. A single squall line can produce ten or more tornados.

Hurricanes A hurricane is a tropical cyclone that has winds of 119 kilometers per hour or higher. They last for about a week and must have warm, moist air and water to keep its strength.

Hurricane Damage When they come ashore, hurricanes cause massive wind damage and brings high waves. The strength of the hurricane and pressure raise the level of the water up to six meters above normal. The result is called a storm surge or a dome of water that sweeps across the coast where the hurricane lands.

Winter Storms Much of the precipitation in the United States falls as snow. All year round, most begins in clouds as snow. If the air is colder than 0 degrees Celsius or 32 degrees Fahrenheit, the precipitation will fall as snow. The ability of air to hold water vapor depends on its temperature. Warm air holds much more water vapor. Think about it…In the summer time, the weatherman always talks about humidity but never seems to in the winter. Lake effect snow