Weather Weather vs Climate Weather describes the shortterm

Weather

Weather vs. Climate • Weather describes the shortterm conditions that are happening in our environment. • Over the course of a week, two weeks or month. • Climate is the average weather that occurs over a 30 - year time period for a particular region. • It is an average pattern of weather.

Weather Instruments

Thermometer • A thermometer measures the air temperature. Most thermometers are closed glass tubes containing liquids such as alcohol or mercury. • When air around the tube heats the liquid, the liquid expands and moves up the tube. • A scale shows what the actual temperature is.

Barometer • A barometer measures air pressure. It tells you whether or not the pressure is rising or falling. • A rising barometer means sunny and dry conditions, while a falling barometer means stormy and wet conditions. • An Italian scientist named Torricelli built the first barometer in 1643.

Rain Gauge

Wind Vane

Anemometer • Measures wind speed and direction. • Cups catch the wind, turning a dial attached to the instrument. • The dial shows the wind speed.

Wind Sock • Measures both wind direction and speed. • Normally used at airports.

Weather Balloon • An expendable device (called a radiosonde) is sent up high into the atmosphere to read various weather conditions. • Measures atmospheric pressure, temperature, humidity and wind speed.

Hygrometer • Measures the amount of humidity or water vapor in the air.

Weather Map • Indicate atmospheric conditions above a large portion of the Earth’s surface. • Meteorologists use Weather Maps to forecast the weather.

Weather Satellite • Used to take pictures and track large-scale air movements. • Meteorologists compile and analyze the data with the help of computers.

Your Eyes • One of the best ways to detect weather! • Always keep an eye on the sky and you can usually figure out the weather conditions.

Forecasting the Weather

Air Pressure • Air has mass and volume. It takes up space. • Even though it is very light, air has weight. • The pressure of air pushes down on the ground the same way our weight pushes down on the ground.

Air movement

Air has A LOT to do with weather!

Pressure Systems High Pressure System Low Pressure System • A whirling mass of cool, dry air • A whirling mass of warm, moist that brings fair weather and light air that brings stormy weather winds. with strong winds. • “A beautiful sunny day!” • “A cloudy, snowy/rainy day. ” • Represented by a big, blue H. • Represented as a big, red L.

Air Pressure

Humidity is the amount of water vapor in the air.

Air Masses • An air mass is an extremely large body of air whose properties of temperature and moisture content (humidity), are the same. • Air masses can control the weather for a relatively long time; from a period of days, to months. • Most weather occurs along the edge of these air masses at boundaries called fronts. • There are 4 major air masses.

Continental Air Mass (c) A cold and dry air mass located over large land masses.

Maritime or Marine Air Mass (m) A cool, moist air mass, located above oceans.

Arctic or Polar Air Mass (P) A cold, dry air mass, located at the poles of the globe (north and south).

Tropical Air Mass (T) A warm, moist air mass located within about 25 degrees of the equator.

We can combine continental (c), marine (m), polar (P) and tropical (T) to describe various types of air masses.

Video:

Weather Fronts What is a Front? • A front is a boundary between two different air masses, resulting in stormy weather. • A front is a line of separation between warm air and cold air. • Characteristics of a front are sharp temperature changes, shifts in wind direction, pressure changes, clouds and precipitation.

Cold Fronts • A boundary between two air masses, one cold and the other warm, moving so that the colder air replaces the warmer air. • Represented with the teeth pointing toward the direction of movement

Warm Front • A boundary between two air masses, one cool and the other warm, moving so that the warmer air replaces the cooler air. • A warm front is represented by a red line with half circles pointing toward the direction of movement.

Occluded Front • A combination of two fronts that form when a cold front catches up and overtakes a warm front. • Represented as a purple line with teeth and half circles.