Tropical Storms and Hurricanes - seawater or freshwater precipitation?

I never experienced a Tropical Storm or Hurricane. I’ve seen lots of tv reporters out in them grabbing light poles to avoid getting swept away.

I know they form at sea and move inward to land. What kind of water do they contain inside the eye and surrounding rainbands?

Is it seawater or freshwater precipitation that will fall from Tropical Storm Issac the next few days?

Rain is freshwater. You see some saltwater flooding from the storm surge along the coast, but that isn’t precipitation.

Um… Physics says - rain is fresh water.

I’d always heard these storms scooped water from the sea as they formed. But, never really knew for sure.

Well yes - the water in the storms comes from the sea - that is, the water evaporates from the sea, rises up, cools down, forms clouds, rain etc. etc. The “evaporates” part makes it fresh.

I’ve been in tropical storms. The rain is definitely fresh, but you can get salt water spray at low levels just from the sea being literally picked up by the wind. This is no different from the salt water spray you get on a normal windy day on the ocean.

I’m being hit by Tropical Storm Isaac right now. It’s still the outer bands, so it’s safe to step outside. Gimme a minute until the next rain band comes through…

Tastes like fresh water to me. Anyone want me to put a cup out and catch some? :slight_smile:


Yep, precipitation comes from water vapor, not actual water being sucked up into the air. When it evaporates, it leaves the salt behind so rain is freshwater. It actually can contain salts, but they are from pollution and things already in the air. Water vapor needs a non-gaseous surface to transition to liquid, so every drop of rain has a piece of dust, pollution, soot, etc in it. Remember that when you try to catch raindrops on your tongue.

Thanks guys. Ignorance fought again. :wink:

I knew how rain formed. But, thought maybe the cyclonic winds in these tropical storms made things different. Now I know it’s still plain ole rain coming down incredibly hard and fast.

You may get a chance to test the theory yourself. :slight_smile:

A decent chunk of the computer models are tracking the storm into the NOLA/southern Louisiana vicinity and then the remnants potentially into TX, LA, AR.

It is even more than just soot or dust; bacteria are actually responsible for the nucleation of most raindrops (although the main species found isn’t pathogenic to humans).

But the rain in Arkansas will mostly be from Arkansas water vapor so it would be hard to conclude that all hurricane rain is freshwater from that alone.

Tropical storms [=all&os_searchfield=University%20Corporation%20for%20Atmospheric%20Research&itemId=OSGC-000-000-010-409&metrics=visible"]transport significant amounts of moisture]([); a lot (most?) of that rain in Arkansas would originate from over the Caribbean and Gulf of Mexico (although the point about fresh vs salt water stands).

But does it fall mainly in the plain?

Your question has been answered, but TS’s do not always move “inward to land.” Steering currents determine where they move, and the steering currents are the upper level cyclones and anticyclones. A weak high pressure above the storm is necessary to maintain sufficient outflow, but adjoining highs will block the storm. A frontal low pressure moving across the States will pick up the TS, the TS will then lose its tropical characteristics (not being associated with any front - which is the leading edge of an air mass - and losing the hot core, characteristic of a TS). Most TS’s are steered back into sea, some headed to England, Africa, etc. If steered north enough so they lose the adiabatic process produced by sea water which temps must be at least 80 degs F, they will also lose their tropical characteristics. Some of these storms make landfall in England. Although they are no longer “tropical” it doesn’t make any difference: winds can still be of hurricane force (<74 mph).

You’re right, sorry. I was thinking how dry air kills hurricanes and how the tropical air from a hurricane is no different than tropical air that gets blown into a region any other time of the year and had some point to tie them together into how you couldn’t tell if you were getting ocean water or normal water, but I actually don’t remember what it was now.