Humidity & Dew Point
What is the dew point?
A: The temperature at which air becomes saturated (full of water) and fog forms.
What type of cloud is associated with thunderstorms?
Cumulonimbus
What kind of front usually brings quick storms followed by cooler air?
What is a cold front?
What does the HRRR model show?
Short-range forecasts for the next 18–48 hours.
Which cloud is high, wispy, and made of ice crystals?
Cirrus
If the temperature is at the dew point, what is the relative humidity?
100%
What are two ingredients needed for a thunderstorm?
1. Moist air (high dewpoint)
2. Rising air (instability)
3. Lifting mechanism (like a front).
What kind of weather do warm fronts usually bring?
Steady rain, layered clouds, and gradual warming.
What is one difference between the HRRR and the GFS?
HRRR = short-range, GFS = long-range
Which cloud is flat and gray and brings drizzle?
Stratus
Why does relative humidity usually drop during the afternoon?
A: Temperature rises, so the air can hold more moisture, lowering RH even if dew point stays the same.
Why is wind shear important for tornado formation?
It helps create rotation inside a thunderstorm.
What happens to the dew point when a cold front passes?
It usually drops quickly.
How can you use dew point maps to detect a cold front?
Look for a sharp boundary where dew point drops quickly.
What happens at the base of a cloud?
Rising air cools to its dew point, and condensation begins.
What does a high dew point tell you about how the air will feel?
It will feel humid and sticky.
What part of a hurricane has the strongest winds and rain?
The eyewall
How can you tell a cold front is approaching by looking at weather data?
Dew point drops, wind shifts to NW, and precipitation increases.
Why does RH change more than dew point during the day?
RH changes with temperature, but dew point stays mostly the same unless the air mass changes.
Which cloud type is white and fluffy and usually means fair weather?
What is cumulus?
On a weather graph, how can you tell when the air might become saturated (full of water)?
When the temperature line and dew point line are very close together.
How does a cold front help trigger thunderstorms?
A cold front forces warm, moist air to rise quickly. As the air rises, it cools to its dew point, causing condensation, cloud formation, and possibly thunderstorms.
Why does warm air rise when it meets a cold front?
Warm air is less dense, so it gets pushed upward by the advancing cold air.
You’re looking at the GFS dew point map. The dew point in Georgia is 74°F, while in Nevada it’s 28°F. What does this tell you about the air in both places, and why is it so different?
Georgia has very humid air from Gulf moisture; Nevada has dry air from desert and mountain effects.
Why are clouds often found at the boundary of a front?
Because warm air is lifted over cooler air, cools to its dew point, and forms clouds.