Meteorology (Fall 2024) PDF

METEOROLO GY CHAPTER 12  METEOROLOGY Meteorology – the study of the physics, chemistry, and dynamics of the atmospheric phenomena Atmospheric Phenomena are classified as types of meteors Hydrometeors – cloud droplets and precipitation – rain, sleet, snow, and hail Lithometeor...

METEOROLO GY CHAPTER 12  METEOROLOGY Meteorology – the study of the physics, chemistry, and dynamics of the atmospheric phenomena Atmospheric Phenomena are classified as types of meteors Hydrometeors – cloud droplets and precipitation – rain, sleet, snow, and hail Lithometeors – smoke, haze, dust and other suspended particles Electrometeors – thunder and lightning  WEATHER VS. CLIMATE Weather – short term variations in atmospheric phenomena that interact and affect the environment and life on Earth (minutes, hours, days, weeks, months or years) – Determines what clothes we wear on a certain day Climate – long-term average of variations in weather for a particular area (Averages over 30 years) – Determines what crops we plant in a certain region  IMBALANCED HEATING AND THERMAL REDISTRIBUTION Why is the average temp. in January in Miami higher that in Detroit? Earth’s axis of rotation is tilted relative to the plane of Earth’s orbit; therefore the number of hours of daylight and amount of solar radiation is greater in Miami Areas around the world maintain about the same average temperatures over time due to the constant movement of air and water among Earth’s surfaces, oceans and atmosphere; providing a constant redistribution of Earth’s thermal energy  AIR MASSES Air mass – large volume of air that has the same characteristics, such as humidity and temperature as its source region Source Region – area over which the air mass forms. Most air masses form over tropical or polar regions Air over a warm surface can be heated by conduction and it rises because it is less dense than the surrounding air which can happen of thousands of square kilometers for days or weeks; this forms an air mass There are five types of air masses that influence weather in the US Arctic, Continental Polar, Continental Tropical, Maritime Polar, Maritime Continental  TYPES OF AIR MASSES Tropical Air Masses – Maritime : Origins are tropical bodies of water. Bring hot, humid air to the eastern 2/3s of North America. – Continental: Mexico and the southwest US are source regions, hot and dry air Polar Air Masses – Maritime: Form over cold waters of the North Atlantic and North Pacific (West Coast, sometimes heavy rain in winter) – Continental: Forms over the interior of Canada and Alaska. Winter – frigid air southward, Summer – cool and dry for summertime relief Arctic: Forms from snow and ice covered regions 60N latitude and above, receive almost no solar radiation through the winter and can bring the coldest of air during winter  AIR MASS MODIFICATION Air masses do not stay in one place, they eventually move transferring thermal energy from one place to another When air masses travel over regions with different characteristics than itself, it can acquire some of the characteristics of that region For example, when a polar air mass travels over a lake, it can acquire some thermal heat but also some moisture, which can lead to Snows  FRONTS Air masses with different characteristics can collide and result in dramatic weather changes Front – narrow region between two air masses of different densities created after two air masses collide 4 types: – Cold Front – Warm Front – Stationary Front – Occluded Front  COLD FRONT When cold dense air displaces warm air, it forces the warm air, which is less dense, up along a steep slope As the warm air rises, it cools and water vapor condenses. Intense precipitation and sometimes thunderstorms are common with cold fronts Represented by a blue line with spaced blue triangles pointing in the direction of the fronts movements  WARM FRONT Advancing warm air displaces cold air Develops a gradual boundary slope Can cause widespread light precipitation Represented by a red line with evenly spaces semi- circles pointing in the direction of the front’s movement  STATIONARY When two air masses meet but FRONT neither advances, the boundary between them stalls Occurs between 2 masses that have small temp and pressure gradients between them The air masses can continue to move parallel to the front Sometimes brings light winds and precipitation Represented by a line of evenly spaced alternating cold and warm air symbols pointing in opposite directions  OCCLUDED FRONT Sometimes a cold air mass moves so rapidly that it overtakes a warm front and forces the warm air upwards The warm air is lifted, the advancing cold air masses collide This produces strong winds and heavy precipitation Represented by a purple line of evenly spaced triangles and semicircles pointing in the direction of the fronts movement  PRESSURE SYSTEMS Sinking air is associated with high pressure Rising air is associated with low pressure Air always flows from an area with high pressure to low pressure When you combine rising or sinking air to the Coriolis Effect, it results in the formation of rotating high or low pressure systems in the atmosphere Coriolis Effect – a force or effect that comes from the Earth’s rotation which deflects moving objects to the right in the Northern hemisphere and to the left in the Southern hemisphere  HIGH VS LOW PRESSURE SYSTEMS In a low pressure system, air rises and is replaced by air outside of the system that spirals inwards towards the center and then upwards In the Northern h. the air moves counter clockwise, its opposite in the Southern h. As the air rises it often cools and condenses into clouds and precipitation In a high pressure system, air sinks and moves away from the systems center when it reaches Earths surface The Coriolis effect causes this air to move towards the right and circulate in a clockwise direction in the Northern H. and counterclockwise in the Southern H Usually associated with fair weather  WEATHER INSTRUMENTS Barometer – Air Pressure Anemometer – Wind Speed Hygrometer – Humidity Thermometer – Temperature Weather Vane – Wind Direction Radiosonde – Reads upper atmosphere weather (large balloon)  STATION MODELS After weather data is gathered, meteorologists plot the data on a map using station models for individual cities or towns Station model – record of weather data for a particular site at a particular time. Allows meteorologists to fit large amounts of data into a small space, and gives them a uniform way to communicate weather data To plot this data, they use lines called Isopleths that connect points of equal or constant values, which represent different weather variables such as pressure or temperature Isobars – represent lines of equal pressure Isotherms – represent lines of equal temperature  INTERPRETING STATION MODEL DATA Remember studying about topographic maps and how they determined different elevation The differences between 2 lines is the contour interval The closer the lines, the steeper the slope, the further the lines, the less steep the slope Remember that air pressure is measured in millibars, therefore, that’s what the numbers on a station model represent Isobars that are close together indicate a large pressure difference over a small area, which means strong winds and vise versa Combining the isobar information with isotherms helps meteorologists to identify fronts HOW TO DRAW STATION MODELS READING AND INTERPRETING WEATHER MAPS You can look at a weather map to answer certain questions such as: – Where is the highest and lowest isobars located – Describe the direction and the strength of the wind – Find the locations with the warmest and coldest temperatures – Predict the weather