Weather Meteorology Weather and Climate Meteorology is the

Weather

Meteorology, Weather, and Climate ● ● Meteorology is the scientific study of the earth's atmosphere Climate is an areas known weather history, temperature, precipitation, wind ○ ● Obtained over a long period of time Weather looks at the same factors as climate except over a short period of time

Working with the Weather ● ● ● Farmers need to know what the weather will be like in advance to make sure that they plant, weed, and harvest at good times Sailors and aviators need to know when there will be bad weather systems in order to avoid certain routes or to delay the route entirely Construction crews need to know when bad weather will hit so that they can make sure they are safe and not working when the weather arrives

Extreme Weather Situation ● ● ● Winter Storms Flash Floods Tornadoes Hurricanes Thunderstorms

Winter Storms ● ● Include ice storms, freezing rain that cause black ice, blizzards, and severe cold Find shelter and try to stay warm, do not work to the point that you start sweating because it can cause frostbite Safety?

Flash Floods ● ● Increased rainfall can cause rivers and canals to flood, this will lead to dangerous flash floods Occurs within 6 hours of the event causing it. Safety?

Hurricanes ● ● ● Hurricanes are massive wind and water storms that form in the ocean and travel to land They cause large storm surge that can cause flooding Winds of 74 mph or more, commonly up to 200 mph. Safety?

Tornadoes ● ● Tornadoes are wind storms that can reach wind speeds of up to 300 mph These are formed when warmer, humid air collides with colder, dry air. When the warm air rises, it causes an updraft forming a funnel cloud. The tornado is only formed once the funnel cloud touches the ground. They are rated on the Fujita scale from F 0 -F 5 Safety?

Thunderstorms ● ● Large storms that have lots of lightning Thunderstorms may have other forms of weather associated, such as tornadoes, hail, flash floods, and strong winds Safety?

Weather Watch vs Weather Warning? Weather Watch ● Issued when the risk of hazardous weather is at a higher than normal risk of occuring. Details of that event, such as intensity or location, are not quite pinpointed. Weather Warning ● Issued when a severe weather condition is approaching or has a very high probability of occuring.

Pressure Systems Atmospheric pressure is the description of weight of the atmosphere on the ground or directly above a location in the air. ● ● Low pressure systems are warmer air, and associated with rising air. High pressure systems are cooler air, and associated with sinking air.

Low Pressure ● ● Low pressure systems are warmer, more humid air. In the US, typically comes from the southeast, as well as other tropical climate regions. Described as a “warm front” Normally brings rain and other precipitation.

High Pressure ● ● High pressure systems are cooler, more dense air Often from a more northern region with a cooler climate. Described as a “cold front” Normally brings calmer weather with less precipitation.

Cold Front

Warm Front

What causes wind, rain lightning, and hail?

Wind Land heats and cools faster than water. Therefore, in the afternoon the land is usually a lot warmer than water next to it. The ground in turn heats the air above it, so the air over the ground becomes warmer than the air over the waters. The air over the ground rises (warm air is lighter than cold air). This creates an area of lower pressure over the land, and air moves in from the sea to replace it. This is what we call a sea breeze. The opposite occurs at night. . . the land cools faster than the sea. Then the air rises offshore, and air moves in from land to replace it. This is called a land breeze.

Wind

Rain Water can come from a variety of sources, but before anything can happen, that water needs to evaporate into the air. When this happens, it becomes invisible water vapor. Air can hold only a certain amount of water vapor, and this amount increases as the temperature gets warmer. When air is holding all the water it can at a given temperature, we say that it is saturated. Now if we take this air and raise it, we lower the air pressure pushing down on it. This in turn forces the temperature to drop. As the air cools, its ability to hold water decreases and eventually it becomes saturated. At this point in the process, clouds begin to form. If we keep lifting the air, it becomes even cooler and even more water condenses into the cloud. The water droplets hit each other and combine to form bigger and bigger water droplets. Eventually the droplets get so big that they can no longer be suspended in the air. At that point it falls out as rain.

Rain

Lightning As a thunderstorm develops, positive and negative charges collect on the ground and in various parts of the cumulonimbus cloud. Charges act a bit like pressure in that the atmosphere is always striving to have charges distributed evenly. Therefore, when the areas of positive and negative charge get large enough, a bolt of electricity jumps from one to the other to equalize the charge. We see this bolt of electricity as lightning. Lightning can be cloud-to-cloud, cloud-to-ground, or even cloud-to-air.

Hail Usually rain falls in a downdraft. Sometimes updrafts can develop below downdrafts. When this occurs, the rain is carried back up into the cloud. If it gets pushed above the freezing level, it will condense into ice. Eventually this ice will begin falling again in a downdraft. This updraft/downdraft process can be repeated many times and the developing hailstone will pick up a layer of ice with each cycle. At some point the ball of ice will be too large for the updraft to support it, and then it will fall as hail. Hail is usually marble-size or smaller and has cycled through the above process 2 -3 times. However, hail as large as softballs have been recorded and these go through the cycle many times.

Clouds Let’s start by listing the clouds by type: Cloud Type Cloud Name Vertically developing clouds (0 -50000 feet) Low Clouds (below 6500 feet) Stratocumulus Middle Clouds (6500 -20000 feet) Altostratus High Clouds (above 20000 feet) Cirrocumulus Cumulonimbus, Cumulus Stratus, Nimbostratus, Altocumulus, Cirrostratus, Cumulonimbus clouds are associated with showers and thunderstorms, while nimbostratus clouds are associated with steady precipitation, like snow and rain. The nimbus or nimbo designation indicates that the clouds are precipitating water or ice. The other clouds typically do not produce precipitation that reaches the ground,

Clouds

What is acid rain? Human activity releases pollutants into the atmosphere. Some of these pollutants contain sulfur particles, and these can mix with water in the atmosphere to form what we call acid rain. The biggest sources of atmospheric sulfur are power plants that burn coal with a high sulfur content. Acid rain tends to occur downwind from these plants, and so the worst areas for acid rain are the northeastern U. S. and southeastern Canada.