Understanding WeatherPrepared by Prof. Craig A. Casillas Barreto

Weather is the condition of the atmosphere at a certain time and place.

The Condition of the Atmosphere is affected by the amount of water that is in the air.

Water in the Air

The Water Cycle

Humidity

Humidity (Practice)

Factor that Affect Relative Humidity

Amount of Water Vapor, because it changes at a constant temperature and Pressure.

Temperature, because the amount of humidity decrease if the temperature rises and increase as the temperature drops.

A Psychrometer is a instrument that is used to measure the relative humidity. It consist of two thermometer, one of which is a wet-bulb thermometer covered with a damp cloth. The other is a dry-bulb thermometer. The difference in temperature of both thermometer indicates the amount of water vapor in the air.

The larger the difference between the two readings, is the less water vapor is in the air and thus lower the humidity is.

Methods to Measure the Relative Humidity

A Cloud is a collection of a small water droplets or ice crystals suspended in the air, which forms when the air is cooled and condensation occurs.

Clouds are classified by form and altitude.

Clouds

There are four major forms of precipitation like: Rain Snow Sleet Hail

Precipitation

Air mass is a large body of air where temperature and moisture content are similar throughout.

The moisture content and temperature of an air mass are determined by the area over which the air mass form. These areas are called source regions.

Air Masses and Fronts

Fronts are boundary between air masses of different densities and usually different temperature.

Fronts

Different air pressure in different areas can affect the weather and forms: Cyclones and Anticyclones.

Cyclone is an area in the atmosphere that has a lower pressure than the surrounding areas and has winds the spiral towards the center.

Anticyclone the rotation of the air around a high-pressure center in the direction opposite to Earth’s rotation.

Air Pressure and Weather

Severe Weathers is a weather that can cause property damage and sometimes death.

Examples of severe weather: Thunderstorms Tornadoes Hurricanes

Severe Weather

Thunderstorms are a usually brief, heavy storm that consist of rain, strong winds, lightning, and thunder.

They can form from: Cold fronts Warm and moist air near Earth’s

surface Unstable atmosphere

They produce: Lightning, thunder and Severe

thunderstorms Lightning is an electric discharge

that occurs between a positively charged area and negatively charge area.

Thunder is the sound that result from the rapid expansion of air along the lightning strike.

Thunderstorms

Tornadoes are destructive, rotating column of air that has a very high wind speeds, is visible as a funnel-shaped cloud, and touches the ground.

Tornadoes

Hurricanes are severe storms that develops over tropical oceans and whose strong winds of more than 120 km/h spiral in toward the intensely lo-pressure storm center.

They are also called Cyclones in Indian Ocean and Typhoons in the Pacific Ocean.

Hurricane

Weather-Forecasting Technology Meteorologist need to measure various

atmospheric conditions, such as: Air Pressure Humidity Precipitation Temperature Wind Speed Wind Direction

Forecasting the Weather

Weather-Forecasting Technology

Radar is used to find the location, movement and amount of precipitation.

Doppler Radar is used to track precipitation.

Weather satellites provide images of weather systems.

Radar and Satellites

Weather Maps shows areas of high and low pressure as well as the location of fronts.

Weather Maps