Weather vs. ClimateLet’s get something straight around here.

WeatherWeather is the sum of all physical properties

such as: temperature, atmospheric pressure, humidity, precipitation, sunshine, cloud cover, and wind direction and speed.

These factors can change from moment to moment and are more easily identifiable by the general public.

Weather is reported to the public by the media.

Increasingly, this reporting is done by people who have no formal training in meteorology.

ClimateClimate is the average long-term weather of an

area.This includes the general pattern of atmospheric or

weather conditions, seasonal variations, and weather extremes averaged over a long period (at least 30 years).

The two main contributing factors include temperature and precipitation.

Climate is monitored by scientists using elaborate and sophisticated models.

Climate change is a current topic of debate, despite clear evidence of its existence.

Climatic RegionsTropical – between 23.5o

North and 23.5o South.Temperate – from Tropical

region to approximately 55o North and 550 South.

Polar – from Temperate region to 90o North and 90o South.

Climate changes from Equator to Pole is mimicked as one moves from sea level up in elevation.

Moving 300 miles toward the poles (from the Equator) is roughly the same as climbing 1000’ in elevation from sea level.

Climatic Regions

Why we have Seasons

Air Circulation

Baltimore ClimateBaltimore, located at 39.2833oN in the mid-Atlantic

coastal region of North America enjoys a maritime temperate climate.

Winters are cool, but not frigid. Precipitation the Winter falls at a steady pace.

Summers are very warm. Precipitation in the Summer is less frequent than Winter.

Spring and Fall are mild. Precipitation falls mostly in the Spring.

The proximity of the Atlantic Ocean offers a stabilizing effect on average annual temperatures.

Why/How?In a word: Specific Heat

Baltimore WeatherWho can predict? Certainly not the meteorologists.Weather is influenced by many factors (the Great

Lakes, the western Maryland mountains, the Chesapeake Bay) but, the Atlantic Ocean primarily drives the weather.

What type of weather would you expect to enjoy on November 12th in Baltimore?

Record High – 76oFRecord Low – 27oFAverage High – 60oFAverage Low – 43oFToday’s High - 49oF (occurred at 3:00 AM)Today’s Low - 33oF (as of 9:30 AM)

Pressure SystemsHigh Pressure generally indicates stable, clear

weather.They rotate in a clockwise direction in the

Northern hemisphere.Low Pressure generally indicates unstable,

stormy weather.They rotate in a counter-clockwise direction in

the Northern hemisphere.This is due to the Coriolis Effect. http://

www.youtube.com/watch?v=i2mec3vgeaIWinds flow from areas of high to low pressure.The greater the pressure difference, the

stronger the winds.

ThunderstormsWhen cold air collides with warm air, the colder

(more dense) air dives under the warmer air.As the warm air is pushed upward, any available

moisture begins to condense in the dropping temperatures.

As this moisture condenses, it releases huge amounts of energy in the form of latent heat.

As this moisture condenses, the cloud begins to become more pronounced and, as it blocks sunlight, a temperature inversion occurs - further dropping the temperature.

As this process continues, the cloud becomes unstable and energy begins to be released through precipitation, wind, and (primarily) lightning.

What it looks like

Now, in an animationhttp://www.youtube.com/watch?

v=bOfOA3PTghM

Types of thunderstormsStorms can occur as

single cells

Multi-cell clusters

Multi-cell lines (squall line)

And Supercells